Digital broadcasting system and method of processing data

ABSTRACT

A digital receiving system, and a method of processing data are disclosed. The digital receiving system includes a receiving unit, a known sequence detector, and a channel equalizer. The receiving unit receives a broadcast signal including mobile service data and main service data. The known sequence detector detects known data linearly inserted in a data group. The channel equalizer performs channel-equalizing on the received mobile service data using the detected known data.

This application claims the benefit of the Korean Patent Application No.10-2008-0064608, filed on Jul. 3, 2008, which is hereby incorporated byreference as if fully set forth herein. Also, this application alsoclaims the benefit of U.S. Provisional Application No. 60/947,984, filedon Jul. 4, 2007, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital broadcasting system andmethod of processing data.

2. Discussion of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the digital broadcast receiving system may bedeteriorated in a poor channel environment. Particularly, sinceresistance to changes in channels and noise is more highly required whenusing portable and/or mobile broadcast receivers, the receivingperformance may be even more deteriorated when transmitting mobileservice data by the VSB transmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital broadcastingsystem and a method of processing data that substantially obviate one ormore problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a digital broadcastingsystem and a method of processing data that are highly resistant tochannel changes and noise.

Another object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can enhance thereceiving performance of a receiving system (or receiver) by having atransmitting system (or transmitter) perform additional encoding onmobile service data, and by having the receiving system (or receiver)perform decoding on the additionally encoded mobile service data as aninverse process of the transmitting system.

A further object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can alsoenhance the receiving performance of a digital broadcast receivingsystem by inserting known data already known in accordance with apre-agreement between the receiving system and the transmitting systemin a predetermined area within a data area.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital broadcast transmitting system includes a service multiplexer anda transmitter. The service multiplexer multiplexes mobile service dataand main service data at pre-determined data rates and, then, transmitsthe multiplexed service data to the transmitter. The transmitterperforms additional encoding on the mobile service data transmitted fromthe service multiplexer and, also, groups a plurality of mobile servicedata packets having encoding performed thereon so as to configure a datagroup.

Herein, the transmitter may multiplex a mobile service data packetincluding the mobile service data and a main service data packetincluding the main service data in packet units and may transmit themultiplexed data packets to a digital broadcast receiving system.Herein, the transmitter may multiplex the data group and the mainservice data packet in a burst structure, wherein the burst section maybe divided in a burst-on section including the data group, and aburst-off section that does not include the data group. The data groupmay be divided into a plurality of regions based upon a degree ofinterference of the main service data. A long known data sequence may beperiodically inserted in the region having no interference with the mainservice data.

In another aspect of the present invention, a digital broadcastreceiving system may use the known data sequence for demodulating andchannel equalizing processes. When receiving only the mobile servicedata, the digital broadcast receiving system turns power on only duringthe burst-on section so as to process the mobile service data.

In another aspect of the present invention, a digital receiving systemincludes a receiving unit, a known sequence detector, and a channelequalizer. The receiving unit receives a broadcast signal includingmobile service data and main service data. The mobile service dataconfigures a data group. The data group is divided into a plurality ofregions. The known data sequences are linearly inserted in some regionsamong the plurality of regions within the data group, and initializationdata are inserted at a beginning portion of each known data sequence,the initialization data being used for initializing a memory included ina trellis encoder of a broadcast transmitting system. The known sequencedetector detects known data linearly inserted in the data group. Thechannel equalizer performs channel-equalizing on the received mobileservice data using the detected known data. N number of known datasequences are inserted in some regions among the plurality of regionswithin the data group. A transmission parameter is inserted between afirst known data sequence and a second known data sequence, among the Nnumber of known data sequences.

The broadcast receiving system further includes a transmission parameterdetector detecting the transmission parameter, and a block decodersymbol-decoding the mobile service data in block units, based upon thedetected transmission parameter.

The broadcast receiving system further includes a power controllercontrolling power based upon the detected transmission parameter,thereby receiving a data group including requested mobile service data.

The data group configures a RS frame, and the RS frame includes at leastone data packet corresponding to the mobile service data, an RS paritygenerated based upon the at least one data packet, and a CRC checksumgenerated based upon the at least one data packet and the RS parity.

The broadcast receiving system further includes a RS frame decoderperforming CRC-decoding and RS-decoding on the mobile service data in RSframe units, thereby correcting errors occurred in the mobile servicedata within the corresponding RS frame.

The broadcast receiving system further includes a derandomaizerderandomizing the RS-decoded mobile service data.

In another aspect of the present invention, a method for processing dataof a receiving system includes receiving a broadcast signal includingmobile service data and main service data, wherein the mobile servicedata configures a data group, wherein the data group is divided into aplurality of regions, wherein known data sequences are linearly insertedin some regions among the plurality of regions within the data group,and wherein initialization data are inserted at a beginning portion ofeach known data sequence, the initialization data being used forinitializing a memory included in a trellis encoder of a broadcasttransmitting system, detecting known data linearly inserted in the datagroup, and channel-equalizing on the received mobile service data byusing the detected known data.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram showing a general structure of adigital broadcasting system according to an embodiment of the presentinvention;

FIG. 2 illustrates a block diagram of a service multiplexer shown inFIG. 1 of the present invention;

FIG. 3 illustrates a block diagram of a transmitter shown in FIG. 1 ofthe present invention;

FIG. 4 illustrates a block diagram of a pre-processor shown in FIG. 3 ofthe present invention;

FIG. 5( a) to FIG. 5( e) illustrate process steps of error correctionencoding and error detection encoding according to an embodiment of thepresent invention;

FIG. 6( a) to FIG. 6( d) illustrate process steps of row permutation insuper frame units according to an embodiment of the present invention;

FIG. 7A and FIG. 7B respectively illustrate examples of data structuresbefore and after in a data deinterleaver of a digital broadcasttransmitting system according to the present invention;

FIG. 8 illustrates a part of data region A of the signal frame shown inFIG. 7A;

FIGS. 9( a) to 9(c) illustrate a data structure (arrangement) oftransmission (Tx) parameters included in a mobile service data region assignaling data;

FIG. 10 illustrates how the signaling data are inserted in a signalframe after interleaving in a broadcast transmitting system according tothe present invention;

FIG. 11 illustrates an example of acquiring mobile service data includedin a particular data group within a burst according to the presentinvention;

FIG. 12 illustrates another example of FIG. 11;

FIG. 13 illustrates an exemplary process of dividing an RS frame forconfiguring a data group according to the present invention;

FIG. 14( a) and FIG. 14( b) illustrate an exemplary process of dividingan RS frame for configuring a data group according to the presentinvention;

FIG. 15 illustrates exemplary operations of a packet multiplexer fortransmitting data groups according to an embodiment of the presentinvention;

FIG. 16 illustrates a block diagram showing a structure of a blockprocessor according to an embodiment of the present invention;

FIG. 17A to FIG. 17C illustrate block views showing exemplary operationsof the symbol encoder having the coding rate of ¼ according to anembodiment of the present invention;

FIG. 18A illustrates a detailed block view of a ½ outer encoderaccording to an embodiment of the present invention;

FIG. 18B illustrates a detailed block view of a ¼ outer encoderaccording to an embodiment of the present invention;

FIG. 19( a) to FIG. 19( c) illustrates a variable length interleavingprocess of a symbol interleaver shown in FIG. 9;

FIG. 20A and FIG. 20B illustrate a block view showing a structure of ablock processor according to another embodiment of the presentinvention;

FIG. 21( a) to FIG. 21( c) illustrate examples of block encoding andtrellis encoding according to an embodiment of the present invention;

FIG. 22 illustrates a block view of a trellis encoding module accordingto an embodiment of present invention;

FIG. 23A and FIG. 23B illustrate a concatenation between a blockprocessor and a trellis encoding module according to the presentinvention;

FIG. 24 illustrates a block view showing a structure of a blockprocessor according to another embodiment of the present invention;

FIG. 25 illustrates a block view showing a structure of a blockprocessor according to yet another embodiment of the present invention;

FIG. 26 illustrates an example wherein a group formatter inserts andtransmits a transmission parameter according to the present invention;

FIG. 27 illustrates an example wherein a block processor inserts andtransmits a transmission parameter according to the present invention;

FIG. 28 illustrates an example wherein a packet formatter inserts andtransmits a transmission parameter according to the present invention;

FIG. 29 illustrates an example wherein a transmission parameteraccording to the present invention is inserted in a fieldsynchronization segment region;

FIG. 30 illustrates a block diagram of a digital broadcast receivingsystem according to the present invention;

FIG. 31 illustrates a data structure showing an example of known databeing periodically inserted in valid data according to the presentinvention;

FIG. 32 is a flow chart illustrating a method of detecting positions ofknown data according to one aspect of the present invention;

FIG. 33 illustrates a block diagram showing a structure of a demodulatorof a digital broadcast receiving system shown in FIG. 30;

FIG. 34 illustrates a detailed block diagram of the demodulator of thedigital broadcast receiving system shown in FIG. 30;

FIG. 35 illustrates a block diagram of a frequency offset estimatoraccording to an embodiment of the present invention;

FIG. 36 illustrates a block diagram of a known data detector and initialfrequency offset estimator according to the present invention;

FIG. 37 illustrates a block diagram of a partial correlator shown inFIG. 36;

FIG. 38 illustrates a second example of the timing recovery unitaccording to the present invention;

FIG. 39( a) and FIG. 39( b) illustrate examples of detecting timingerror in a time domain;

FIG. 40( a) and FIG. 40( b) illustrate other examples of detectingtiming error in a time domain;

FIG. 41 illustrates an example of detecting timing error usingcorrelation values of FIG. 39 and FIG. 40;

FIG. 42 illustrates an example of a timing error detector according tothe present invention;

FIG. 43 illustrates an example of detecting timing error in a frequencydomain according to an embodiment of the present invention;

FIG. 44 illustrates another example of a timing error detector accordingto the present invention;

FIG. 45 illustrates a block diagram of a DC remover according to anembodiment of the present invention;

FIG. 46 illustrates an example of shifting sample data inputted to a DCestimator shown in FIG. 45;

FIG. 47 illustrates a block diagram of a DC remover according to anotherembodiment of the present invention;

FIG. 48 is a flow chart illustrating a channel equalization methodaccording to one aspect of the present invention;

FIG. 49 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 50 illustrates a detailed block diagram of an example of aremaining carrier phase error estimator according to the presentinvention;

FIG. 51 illustrates a block diagram of a phase error detector obtaininga remaining carrier phase error and phase noise according to the presentinvention;

FIG. 52 illustrates a phase compensator according to an embodiment ofthe present invention;

FIG. 53 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 54 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 55 illustrates a block diagram of another example of a channelequalizer according to the present invention;

FIG. 56 illustrates a block diagram of an example of a CIR estimatoraccording to the present invention;

FIG. 57 illustrates a block diagram of an example of a block decoderaccording to the present invention;

FIG. 58 and FIG. 59 illustrate process steps of error correctiondecoding according to yet another embodiment of the present invention;

FIG. 60 illustrates another example of a digital broadcast receivingsystem according to the present invention.

FIG. 61 illustrates a block diagram of a transmission parameter detectorshown in FIG. 60 in detail;

FIG. 62 illustrates a block diagram of a mode detector shown in FIG. 61in detail;

FIG. 63 illustrates an example of a burst information detectoroutputting a group indicator;

FIG. 64 illustrates an example of a burst information detectoroutputting a burst indicator;

FIG. 65 illustrates an example of comparing actual on/off times andburst sections;

FIG. 66 illustrates a block diagram of a receiving system according toan embodiment of the present invention;

FIG. 67 illustrates a bit stream syntax for a VCT according to thepresent invention;

FIG. 68 illustrates a service_type field according to an embodiment ofthe present invention;

FIG. 69 illustrates a service location descriptor according to anembodiment of the present invention;

FIG. 70 illustrates examples that may be assigned to the stream_typefield according to the present invention;

FIG. 71 illustrates a bit stream syntax for an EIT according to thepresent invention; and

FIG. 72 illustrates a block diagram of a receiving system according toanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system. Additionally,in the present invention, mobile service data may include at least oneof mobile service data, pedestrian service data, and handheld servicedata, and are collectively referred to as mobile service data forsimplicity. Herein, the mobile service data not only correspond tomobile/pedestrian/handheld service data (M/P/H service data) but mayalso include any type of service data with mobile or portablecharacteristics. Therefore, the mobile service data according to thepresent invention are not limited only to the M/P/H service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be serviced as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls & surveys,interactive education broadcast programs, gaming services, servicesproviding information on synopsis, character, background music, andfilming sites of soap operas or series, services providing informationon past match scores and player profiles and achievements, and servicesproviding information on product information and programs classified byservice, medium, time, and theme enabling purchase orders to beprocessed. Herein, the present invention is not limited only to theservices mentioned above. In the present invention, the transmittingsystem provides backward compatibility in the main service data so as tobe received by the conventional receiving system. Herein, the mainservice data and the mobile service data are multiplexed to the samephysical channel and then transmitted.

The transmitting system according to the present invention performsadditional encoding on the mobile service data and inserts the dataalready known by the receiving system and transmitting system (i.e.,known data), thereby transmitting the processed data. Therefore, whenusing the transmitting system according to the present invention, thereceiving system may receive the mobile service data during a mobilestate and may also receive the mobile service data with stabilitydespite various distortion and noise occurring within the channel.

General Description of a Transmitting System

FIG. 1 illustrates a block diagram showing a general structure of adigital broadcast transmitting system according to an embodiment of thepresent invention. Herein, the digital broadcast transmitting includes aservice multiplexer 100 and a transmitter 200. Herein, the servicemultiplexer 100 is located in the studio of each broadcast station, andthe transmitter 200 is located in a site placed at a predetermineddistance from the studio. The transmitter 200 may be located in aplurality of different locations. Also, for example, the plurality oftransmitters may share the same frequency. And, in this case, theplurality of transmitters receives the same signal. Accordingly, in thereceiving system, a channel equalizer may compensate signal distortion,which is caused by a reflected wave, so as to recover the originalsignal. In another example, the plurality of transmitters may havedifferent frequencies with respect to the same channel.

A variety of methods may be used for data communication each of thetransmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of the8VSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSBmode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional encoding isperformed on the mobile service data. Thereafter, the additionallyencoded mobile service data are multiplexed with the main service datato a TS packet form, which is then transmitted. At this point, the datarate of the multiplexed TS packet is approximately 19.39 Mbps.

At this point, the service multiplexer 100 receives at least one type ofmobile service data and program specific information (PSI)/program andsystem information protocol (PSIP) table data for each mobile serviceand encapsulates the received data to each transport stream (TS) packet.Also, the service multiplexer 100 receives at least one type of mainservice data and PSI/PSIP table data for each main service so as toencapsulate the received data to a TS packet. Subsequently, the TSpackets are multiplexed according to a predetermined multiplexing ruleand outputs the multiplexed packets to the transmitter 200.

Service Multiplexer

FIG. 2 illustrates a block diagram showing an example of the servicemultiplexer. The service multiplexer includes a controller 110 forcontrolling the overall operations of the service multiplexer, aPSI/PSIP generator 120 for the main service, a PSI/PSIP generator 130for the mobile service, a null packet generator 140, a mobile servicemultiplexer 150, and a transport multiplexer 160. The transportmultiplexer 160 may include a main service multiplexer 161 and atransport stream (TS) packet multiplexer 162. Referring to FIG. 2, atleast one type of compression encoded main service data and the PSI/PSIPtable data generated from the PSI/PSIP generator 120 for the mainservice are inputted to the main service multiplexer 161 of thetransport multiplexer 160. The main service multiplexer 161 encapsulateseach of the inputted main service data and PSI/PSIP table data to MPEG-2TS packet forms. Then, the MPEG-2 TS packets are multiplexed andoutputted to the TS packet multiplexer 162. Herein, the data packetbeing outputted from the main service multiplexer 161 will be referredto as a main service data packet for simplicity.

Thereafter, at least one type of the compression encoded mobile servicedata and the PSI/PSIP table data generated from the PSI/PSIP generator130 for the mobile service are inputted to the mobile servicemultiplexer 150. The mobile service multiplexer 150 encapsulates each ofthe inputted mobile service data and PSI/PSIP table data to MPEG-TSpacket forms. Then, the MPEG-2 TS packets are multiplexed and outputtedto the TS packet multiplexer 162. Herein, the data packet beingoutputted from the mobile service multiplexer 150 will be referred to asa mobile service data packet for simplicity. At this point, thetransmitter 200 requires identification information in order to identifyand process the main service data packet and the mobile service datapacket. Herein, the identification information may use valuespre-decided in accordance with an agreement between the transmittingsystem and the receiving system, or may be configured of a separate setof data, or may modify predetermined location value with in thecorresponding data packet. As an example of the present invention, adifferent packet identifier (PID) may be assigned to identify each ofthe main service data packet and the mobile service data packet.

In another example, by modifying a synchronization data byte within aheader of the mobile service data, the service data packet may beidentified by using the synchronization data byte value of thecorresponding service data packet. For example, the synchronization byteof the main service data packet directly outputs the value decided bythe ISO/IEC13818-1 standard (i.e., 0x47) without any modification. Thesynchronization byte of the mobile service data packet modifies andoutputs the value, thereby identifying the main service data packet andthe mobile service data packet. Conversely, the synchronization byte ofthe main service data packet is modified and outputted, whereas thesynchronization byte of the mobile service data packet is directlyoutputted without being modified, thereby enabling the main service datapacket and the mobile service data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, or only a portion of the synchronization byte may beinversed. As described above, any type of identification information maybe used to identify the main service data packet and the mobile servicedata packet. Therefore, the scope of the present invention is notlimited only to the example set forth in the description of the presentinvention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39−K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification. Herein, thetransport multiplexer 160 multiplexes the main service data packet beingoutputted from the main service multiplexer 161 and the mobile servicedata packet being outputted from the mobile service multiplexer 150.Thereafter, the transport multiplexer 160 transmits the multiplexed datapackets to the transmitter 200.

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. In this case, the mobileservice multiplexer 150 multiplexes and outputs null data packetsgenerated from the null packet generator 140 so that the output datarate can reach K Mbps. More specifically, in order to match the outputdata rate of the mobile service multiplexer 150 to a constant data rate,the null packet generator 140 generates null data packets, which arethen outputted to the mobile service multiplexer 150. For example, whenthe service multiplexer 100 assigns K Mbps of the 19.39 Mbps to themobile service data, and when the remaining (19.39−K) Mbps is,therefore, assigned to the main service data, the data rate of themobile service data that are multiplexed by the service multiplexer 100actually becomes lower than K Mbps. This is because, in case of themobile service data, the pre-processor of the transmitting systemperforms additional encoding, thereby increasing the amount of data.Eventually, the data rate of the mobile service data, which may betransmitted from the service multiplexer 100, becomes smaller than KMbps.

For example, since the pre-processor of the transmitter performs anencoding process on the mobile service data at a coding rate of at least½, the amount of the data outputted from the pre-processor is increasedto more than twice the amount of the data initially inputted to thepre-processor. Therefore, the sum of the data rate of the main servicedata and the data rate of the mobile service data, both beingmultiplexed by the service multiplexer 100, becomes either equal to orsmaller than 19.39 Mbps. Therefore, in order to match the data rate ofthe data that are finally outputted from the service multiplexer 100 toa constant data rate (e.g., 19.39 Mbps), an amount of null data packetscorresponding to the amount of lacking data rate is generated from thenull packet generator 140 and outputted to the mobile servicemultiplexer 150.

Accordingly, the mobile service multiplexer 150 encapsulates each of themobile service data and the PSI/PSIP table data that are being inputtedto a MPEG-2 TS packet form. Then, the above-described TS packets aremultiplexed with the null data packets and, then, outputted to the TSpacket multiplexer 162. Thereafter, the TS packet multiplexer 162multiplexes the main service data packet being outputted from the mainservice multiplexer 161 and the mobile service data packet beingoutputted from the mobile service multiplexer 150 and transmits themultiplexed data packets to the transmitter 200 at a data rate of 19.39Mbps.

According to an embodiment of the present invention, the mobile servicemultiplexer 150 receives the null data packets. However, this is merelyexemplary and does not limit the scope of the present invention. Inother words, according to another embodiment of the present invention,the TS packet multiplexer 162 may receive the null data packets, so asto match the data rate of the finally outputted data to a constant datarate. Herein, the output path and multiplexing rule of the null datapacket is controlled by the controller 110. The controller 110 controlsthe multiplexing processed performed by the mobile service multiplexer150, the main service multiplexer 161 of the transport multiplexer 160,and the TS packet multiplexer 162, and also controls the null datapacket generation of the null packet generator 140. At this point, thetransmitter 200 discards the null data packets transmitted from theservice multiplexer 100 instead of transmitting the null data packets.

Further, in order to allow the transmitter 200 to discard the null datapackets transmitted from the service multiplexer 100 instead oftransmitting them, identification information for identifying the nulldata packet is required. Herein, the identification information may usevalues pre-decided in accordance with an agreement between thetransmitting system and the receiving system. For example, the value ofthe synchronization byte within the header of the null data packet maybe modified so as to be used as the identification information.Alternatively, a transport_error indicator flag may also be used as theidentification information.

In the description of the present invention, an example of using thetransport_error_indicator flag as the identification information will begiven to describe an embodiment of the present invention. In this case,the transport_error_indicator flag of the null data packet is set to‘1’, and the transport_error_indicator flag of the remaining datapackets are reset to ‘0’, so as to identify the null data packet. Morespecifically, when the null packet generator 140 generates the null datapackets, if the transport_error_indicator flag from the header field ofthe null data packet is set to ‘1’ and then transmitted, the null datapacket may be identified and, therefore, be discarded. In the presentinvention, any type of identification information for identifying thenull data packets may be used. Therefore, the scope of the presentinvention is not limited only to the examples set forth in thedescription of the present invention.

According to another embodiment of the present invention, a transmissionparameter may be included in at least a portion of the null data packet,or at least one table or an operations and maintenance (OM) packet (orOMP) of the PSI/PSIP table for the mobile service. In this case, thetransmitter 200 extracts the transmission parameter and outputs theextracted transmission parameter to the corresponding block and alsotransmits the extracted parameter to the receiving system if required.More specifically, a packet referred to as an OMP is defined for thepurpose of operating and managing the transmitting system. For example,the OMP is configured in accordance with the MPEG-2 TS packet format,and the corresponding PID is given the value of 0x1FFA. The OMP isconfigured of a 4-byte header and a 184-byte payload. Herein, among the184 bytes, the first byte corresponds to an OM_type field, whichindicates the type of the OM packet.

In the present invention, the transmission parameter may be transmittedin the form of an OMP. And, in this case, among the values of thereserved fields within the OM_type field, a pre-arranged value is used,thereby indicating that the transmission parameter is being transmittedto the transmitter 200 in the form of an OMP. More specifically, thetransmitter 200 may find (or identify) the OMP by referring to the PID.Also, by parsing the OM_type field within the OMP, the transmitter 200can verify whether a transmission parameter is included after theOM_type field of the corresponding packet. The transmission parametercorresponds to supplemental data required for processing mobile servicedata from the transmitting system and the receiving system.

Herein, the transmission parameter may include data group information,region information within the data group, RS frame information, superframe information, burst information, turbo code information, and RScode information. The burst information may include burst sizeinformation, burst period information, and time information to nextburst. The burst period signifies the period at which the bursttransmitting the same mobile service is repeated. The data groupincludes a plurality of mobile service data packets, and a plurality ofsuch data groups is gathered (or grouped) to form a burst. A burstsection signifies the beginning of a current burst to the beginning of anext burst. Herein, the burst section is classified as a section thatincludes the data group (also referred to as a burst-on section), and asection that does not include the data group (also referred to as aburst-off section). A burst-on section is configured of a plurality offields, wherein one field includes one data group.

The transmission parameter may also include information on how signalsof a symbol domain are encoded in order to transmit the mobile servicedata, and multiplexing information on how the main service data and themobile service data or various types of mobile service data aremultiplexed. The information included in the transmission parameter ismerely exemplary to facilitate the understanding of the presentinvention. And, the adding and deleting of the information included inthe transmission parameter may be easily modified and changed by anyoneskilled in the art. Therefore, the present invention is not limited tothe examples proposed in the description set forth herein. Furthermore,the transmission parameters may be provided from the service multiplexer100 to the transmitter 200. Alternatively, the transmission parametersmay also be set up by an internal controller (not shown) within thetransmitter 200 or received from an external source.

Transmitter

FIG. 3 illustrates a block diagram showing an example of the transmitter200 according to an embodiment of the present invention. Herein, thetransmitter 200 includes a demultiplexer 210, a packet jitter mitigator220, a pre-processor 230, a packet multiplexer 240, a post-processor250, a synchronization (sync) multiplexer 260, and a transmission unit270. Herein, when a data packet is received from the service multiplexer100, the demultiplexer 210 should identify whether the received datapacket corresponds to a main service data packet, a mobile service datapacket, or a null data packet. For example, the demultiplexer 210 usesthe PID within the received data packet so as to identify the mainservice data packet and the mobile service data packet. Then, thedemultiplexer 210 uses a transport_error_indicator field to identify thenull data packet. The main service data packet identified by thedemultiplexer 210 is outputted to the packet jitter mitigator 220, themobile service data packet is outputted to the pre-processor 230, andthe null data packet is discarded. If a transmission parameter isincluded in the null data packet, then the transmission parameter isfirst extracted and outputted to the corresponding block. Thereafter,the null data packet is discarded.

The pre-processor 230 performs an additional encoding process of themobile service data included in the service data packet, which isdemultiplexed and outputted from the demultiplexer 210. Thepre-processor 230 also performs a process of configuring a data group sothat the data group may be positioned at a specific place in accordancewith the purpose of the data, which are to be transmitted on atransmission frame. This is to enable the mobile service data to respondswiftly and strongly against noise and channel changes. Thepre-processor 230 may also refer to the transmission parameter whenperforming the additional encoding process. Also, the pre-processor 230groups a plurality of mobile service data packets to configure a datagroup. Thereafter, known data, mobile service data, RS parity data, andMPEG header are allocated to pre-determined areas within the data group.

Pre-Processor within Transmitter

FIG. 4 illustrates a block diagram showing an example of thepre-processor 230 according to the present invention. The pre-processor230 includes a data randomizer 301, a RS frame encoder 302, a blockprocessor 303, a group formatter 304, a data deinterleaver 305, a packetformatter 306. The data randomizer 301 within the above-describedpre-processor 230 randomizes the mobile service data packet includingthe mobile service data that is inputted through the demultiplexer 210.Then, the data randomizer 301 outputs the randomized mobile service datapacket to the RS frame encoder 302. At this point, since the datarandomizer 301 performs the randomizing process on the mobile servicedata, the randomizing process that is to be performed by the datarandomizer 251 of the post-processor 250 on the mobile service data maybe omitted. The data randomizer 301 may also discard the synchronizationbyte within the mobile service data packet and perform the randomizingprocess. This is an option that may be chosen by the system designer. Inthe example given in the present invention, the randomizing process isperformed without discarding the synchronization byte within the mobileservice data packet.

The RS frame encoder 302 groups a plurality of mobile thesynchronization byte within the mobile service data packets that israndomized and inputted, so as to create a RS frame. Then, the RS frameencoder 302 performs at least one of an error correction encodingprocess and an error detection encoding process in RS frame units.Accordingly, robustness may be provided to the mobile service data,thereby scattering group error that may occur during changes in afrequency environment, thereby enabling the mobile service data torespond to the frequency environment, which is extremely vulnerable andliable to frequent changes. Also, the RS frame encoder 302 groups aplurality of RS frame so as to create a super frame, thereby performinga row permutation process in super frame units. The row permutationprocess may also be referred to as a row interleaving process.Hereinafter, the process will be referred to as row permutation forsimplicity.

More specifically, when the RS frame encoder 302 performs the process ofpermuting each row of the super frame in accordance with apre-determined rule, the position of the rows within the super framebefore and after the row permutation process is changed. If the rowpermutation process is performed by super frame units, and even thoughthe section having a plurality of errors occurring therein becomes verylong, and even though the number of errors included in the RS frame,which is to be decoded, exceeds the extent of being able to becorrected, the errors become dispersed within the entire super frame.Thus, the decoding ability is even more enhanced as compared to a singleRS frame.

At this point, as an example of the present invention, RS-encoding isapplied for the error correction encoding process, and a cyclicredundancy check (CRC) encoding is applied for the error detectionprocess. When performing the RS-encoding, parity data that are used forthe error correction are generated. And, when performing the CRCencoding, CRC data that are used for the error detection are generated.The RS encoding is one of forward error correction (FEC) methods. TheFEC corresponds to a technique for compensating errors that occur duringthe transmission process. The CRC data generated by CRC encoding may beused for indicating whether or not the mobile service data have beendamaged by the errors while being transmitted through the channel. Inthe present invention, a variety of error detection coding methods otherthan the CRC encoding method may be used, or the error correction codingmethod may be used to enhance the overall error correction ability ofthe receiving system. Herein, the RS frame encoder 302 refers to apre-determined transmission parameter and/or the transmission parameterprovided from the service multiplexer 100 so as to perform operationsincluding RS frame configuration, RS encoding, CRC encoding, super frameconfiguration, and row permutation in super frame units.

RS Frame Encoder within Pre-Processor

FIG. 5( a) to FIG. 5( e) illustrate error correction encoding and errordetection encoding processed according to an embodiment of the presentinvention. More specifically, the RS frame encoder 302 first divides theinputted mobile service data bytes to units of a predetermined length.The predetermined length is decided by the system designer. And, in theexample of the present invention, the predetermined length is equal to187 bytes, and, therefore, the 187-byte unit will be referred to as apacket for simplicity. For example, when the mobile service data thatare being inputted, as shown in FIG. 5( a), correspond to a MPEGtransport packet stream configured of 188-byte units, the firstsynchronization byte is removed, as shown in FIG. 5( b), so as toconfigure a 187-byte unit. Herein, the synchronization byte is removedbecause each mobile service data packet has the same value.

Herein, the process of removing the synchronization byte may beperformed during a randomizing process of the data randomizer 301 in anearlier process. In this case, the process of the removing thesynchronization byte by the RS frame encoder 302 may be omitted.Moreover, when adding synchronization bytes from the receiving system,the process may be performed by the data derandomizer instead of the RSframe decoder. Therefore, if a removable fixed byte (e.g.,synchronization byte) does not exist within the mobile service datapacket that is being inputted to the RS frame encoder 302, or if themobile service data that are being inputted are not configured in apacket format, the mobile service data that are being inputted aredivided into 187-byte units, thereby configuring a packet for each187-byte unit.

Subsequently, as shown in FIG. 5( c), N number of packets configured of187 bytes is grouped to configure a RS frame. At this point, the RSframe is configured as a RS frame having the size of N(row)*187(column)bytes, in which 187-byte packets are sequentially inputted in a rowdirection. In order to simplify the description of the presentinvention, the RS frame configured as described above will also bereferred to as a first RS frame. More specifically, only pure mobileservice data are included in the first RS frame, which is the same asthe structure configured of 187 N-byte rows. Thereafter, the mobileservice data within the RS frame are divided into an equal size. Then,when the divided mobile service data are transmitted in the same orderas the input order for configuring the RS frame, and when one or moreerrors have occurred at a particular point during thetransmitting/receiving process, the errors are clustered (or gathered)within the RS frame as well. In this case, the receiving system uses aRS erasure decoding method when performing error correction decoding,thereby enhancing the error correction ability. At this point, the Nnumber of columns within the N number of RS frame includes 187 bytes, asshown in FIG. 5( c).

In this case, a (Nc,Kc)-RS encoding process is performed on each column,so as to generate Nc−Kc(=P) number of parity bytes. Then, the newlygenerated P number of parity bytes is added after the very last byte ofthe corresponding column, thereby creating a column of (187+P) bytes.Herein, as shown in FIG. 5( c), Kc is equal to 187 (i.e., Kc=187), andNc is equal to 187+P (i.e., Nc=187+P). For example, when P is equal to48, (235,187)-RS encoding process is performed so as to create a columnof 235 bytes. When such RS encoding process is performed on all N numberof columns, as shown in FIG. 5( c), a RS frame having the size ofN(row)*(187+P) (column) bytes may be created, as shown in FIG. 5( d). Inorder to simplify the description of the present invention, the RS framehaving the RS parity inserted therein will be referred to as s second RSframe. More specifically, the second RS frame having the structure of(187+P) rows configured of N bytes may be configured.

As shown in FIG. 5( c) or FIG. 5( d), each row of the RS frame isconfigured of N bytes. However, depending upon channel conditionsbetween the transmitting system and the receiving system, error may beincluded in the RS frame. When errors occur as described above, CRC data(or CRC code or CRC checksum) may be used on each row unit in order toverify whether error exists in each row unit. The RS frame encoder 302may perform CRC encoding on the mobile service data being RS encoded soas to create (or generate) the CRC data. The CRC data being generated byCRC encoding may be used to indicate whether the mobile service datahave been damaged while being transmitted through the channel.

The present invention may also use different error detection encodingmethods other than the CRC encoding method. Alternatively, the presentinvention may use the error correction encoding method to enhance theoverall error correction ability of the receiving system. FIG. 5( e)illustrates an example of using a 2-byte (i.e., 16-bit) CRC checksum asthe CRC data. Herein, a 2-byte CRC checksum is generated for N number ofbytes of each row, thereby adding the 2-byte CRC checksum at the end ofthe N number of bytes. Thus, each row is expanded to (N+2) number ofbytes. Equation 1 below corresponds to an exemplary equation forgenerating a 2-byte CRC checksum for each row being configured of Nnumber of bytes.

g(x)=x ¹⁶ +x ¹² +x ⁵+1  Equation 1

The process of adding a 2-byte checksum in each row is only exemplary.Therefore, the present invention is not limited only to the exampleproposed in the description set forth herein. In order to simplify theunderstanding of the present invention, the RS frame having the RSparity and CRC checksum added therein will hereinafter be referred to asa third RS frame. More specifically, the third RS frame corresponds to(187+P) number of rows each configured of (N+2) number of bytes. Asdescribed above, when the process of RS encoding and CRC encoding arecompleted, the (N*187)-byte RS frame is expanded to a (N+2)*(187+P)-byteRS frame.

Based upon an error correction scenario of a RS frame, the data byteswithin the RS frame are transmitted through a channel in a rowdirection. At this point, when a large number of errors occur during alimited period of transmission time, errors also occur in a rowdirection within the RS frame being processed with a decoding process inthe receiving system. However, in the perspective of RS encodingperformed in a column direction, the errors are shown as beingscattered. Therefore, error correction may be performed moreeffectively. At this point, a method of increasing the number of paritydata bytes (P) may be used in order to perform a more intense errorcorrection process. However, using this method may lead to a decrease intransmission efficiency. Therefore, a mutually advantageous method isrequired. Furthermore, when performing the decoding process, an erasuredecoding process may be used to enhance the error correctionperformance.

The RS frame encoder according to the present invention also performs arow permutation (or interleaving) process in super frame units in orderto further enhance the error correction performance when errorcorrection the RS frame. FIG. 6 illustrates an example of performing arow permutation (or interleaving) process in super frame units accordingto the present invention. More specifically, G number of RS framesencoded as shown in FIG. 5 is grouped to form a super frame, as shown inFIG. 6( a). At this point, since each RS frame is formed of(N+2)*(187+P) number of bytes, one super frame is configured to have thesize of (N+2)*(187+P)*G bytes.

When a row permutation process permuting each row of the super frameconfigured as described above is performed based upon a pre-determinedpermutation rule, the positions of the rows prior to and after beingpermuted (or interleaved) within the super frame may be altered. Morespecifically, the i^(th) row of the super frame prior to theinterleaving process, as shown in FIG. 6( b), is positioned in the j rowof the same super frame after the row permutation process. Theabove-described relation between i and j can be easily understood withreference to a permutation rule as shown in Equation 2 below.

j=G(i mod(187+P))+└i/(187+P)┘

i=(187+P)(j mod G+└j/G┘

where 0≦i, j≦(187+P)G−1; or

where 0≦i, j<(187+P)G  Equation 2

Herein, each row of the super frame is configured of (N+2) number ofdata bytes even after being row-permuted in super frame units.

When all row permutation processes in super frame units are completed,the super frame is once again divided into G number of row-permuted RSframes, as shown in FIG. 6( d), and then provided to the block processor303. Herein, the number of RS parity bytes and the number of columnsshould be equally provided in each of the RS frames, which configure asuper frame. As described in the error correction scenario of a RSframe, in case of the super frame, a section having a large number oferror occurring therein is so long that, even when one RS frame that isto be decoded includes an excessive number of errors (i.e., to an extentthat the errors cannot be corrected), such errors are scatteredthroughout the entire super frame. Therefore, in comparison with asingle RS frame, the decoding performance of the super frame is moreenhanced. As described above, the mobile service data being encoded onRS frame units and row-permuted in super frame units by the RS frameencoders 302 are outputted to the block processor 303.

As described above, the mobile service data encoded by the RS frameencoder 302 are inputted to the block processor 303. The block processor303 then encodes the inputted mobile service data at a coding rate ofD/E (wherein, D is smaller than E (i.e., D<E)) and then outputted to thegroup formatter 304. More specifically, the block processor 303 dividesthe mobile service data being inputted in byte units into bit units.Then, the D number of bits is encoded to E number of bits. Thereafter,the encoded bits are converted back to byte units and then outputted.For example, if 1 bit of the input data is coded to 2 bits andoutputted, then D is equal to 1 and E is equal to 2 (i.e., D=1 and E=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then D is equal to 1 and E is equal to 4 (i.e., D=1 and E=4).Hereinafter, the former coding rate will be referred to as a coding rateof ½ (½-rate coding), and the latter coding rate will be referred to asa coding rate of ¼ (¼-rate coding), for simplicity.

Herein, when using the ¼ coding rate, the coding efficiency is greaterthan when using the ½ coding rate, and may, therefore, provide greaterand enhanced error correction ability. For such reason, when it isassumed that the data encoded at a ¼ coding rate in the group formatter304, which is located near the end portion of the system, are allocatedto an area in which the receiving performance may be deteriorated, andthat the data encoded at a ½ coding rate are allocated to an area havingexcellent receiving performance, the difference in performance may bereduced. At this point, the block processor 303 may also receivesignaling information including transmission parameters. Herein, thesignaling information may also be processed with either ½-rate coding or¼-rate coding as in the step of processing mobile service data.Thereafter, the signaling information is also considered the same as themobile service data and processed accordingly.

Meanwhile, the group formatter inserts mobile service data that areoutputted from the block processor 303 in corresponding areas within adata group, which is configured in accordance with a pre-defined rule.Also, with respect to the data deinterleaving process, each place holderor known data (or known data place holders) are also inserted incorresponding areas within the data group. At this point, the data groupmay be divided into at least one hierarchical area. Herein, the type ofmobile service data being inserted in each area may vary depending uponthe characteristics of each hierarchical area. Additionally, each areamay, for example, be divided based upon the receiving performance withinthe data group. Furthermore, one data group may be configured to includea set of field synchronization data.

In an example given in the present invention, a data group is dividedinto A, B, and C regions in a data configuration prior to datadeinterleaving. At this point, the group formatter 304 allocates themobile service data, which are inputted after being RS encoded and blockencoded, to each of the corresponding regions by referring to thetransmission parameter. FIG. 7A illustrates an alignment of data afterbeing data interleaved and identified, and FIG. 7B illustrates analignment of data before being data interleaved and identified. Morespecifically, a data structure identical to that shown in FIG. 7A istransmitted to a receiving system. Also, the data group configured tohave the same structure as the data structure shown in FIG. 7A isinputted to the data deinterleaver 305.

As described above, FIG. 7A illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.7A, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type of mobileservice data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the mainservice data. Herein, the data group is divided into a plurality ofregions to be used for different purposes. More specifically, a regionof the main service data having no interference or a very lowinterference level may be considered to have a more resistant (orstronger) receiving performance as compared to regions having higherinterference levels. Additionally, when using a system inserting andtransmitting known data in the data group, and when consecutively longknown data are to be periodically inserted in the mobile service data,the known data having a predetermined length may be periodicallyinserted in the region having no interference from the main service data(e.g., region A). However, due to interference from the main servicedata, it is difficult to periodically insert known data and also toinsert consecutively long known data to a region having interferencefrom the main service data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 7A. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of mobile service data bytes that can beinserted in each hierarchically divided region of FIG. 7A are merelyexamples given to facilitate the understanding of the present invention.Herein, the group formatter 304 creates a data group including places inwhich field synchronization data bytes are to be inserted, so as tocreate the data group that will hereinafter be described in detail.

More specifically, region A is a region within the data group in which along known data sequence may be periodically inserted, and in whichincludes regions wherein the main service data are not mixed (e.g., A2to A5). Also, region A includes a region (e.g., A1) located between afield synchronization region and the region in which the first knowndata sequence is to be inserted. The field synchronization region hasthe length of one segment (i.e., 832 symbols) existing in an ATSCsystem.

For example, referring to FIG. 7A, 2428 bytes of the mobile service datamay be inserted in region A1, 2580 bytes may be inserted in region A2,2772 bytes may be inserted in region A3, 2472 bytes may be inserted inregion A4, and 2772 bytes may be inserted in region A5. Herein, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the mobile service data. As described above, when region Aincludes a known data sequence at both ends, the receiving system useschannel information that can obtain known data or field synchronizationdata, so as to perform equalization, thereby providing enforcedequalization performance.

Also, region B includes a region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1) (e.g., region B1), and aregion located within 8 segments behind the very last known datasequence which is inserted in the data group (e.g., region B2). Forexample, 930 bytes of the mobile service data may be inserted in theregion B1, and 1350 bytes may be inserted in region B2. Similarly,trellis initialization data or known data, MPEG header, and RS parityare not included in the mobile service data. In case of region B, thereceiving system may perform equalization by using channel informationobtained from the field synchronization region. Alternatively, thereceiving system may also perform equalization by using channelinformation that may be obtained from the last known data sequence,thereby enabling the system to respond to the channel changes.

Region C includes a region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A) (e.g., region C1), a regionlocated within 12 segments including and following the 9^(th) segment ofthe very last known data sequence within the data group (chronologicallylocated after region A) (e.g., region C2), and a region located in 32segments after the region C2 (e.g., region C3). For example, 1272 bytesof the mobile service data may be inserted in the region C1, 1560 bytesmay be inserted in region C2, and 1312 bytes may be inserted in regionC3. Similarly, trellis initialization data or known data, MPEG header,and RS parity are not included in the mobile service data. Herein,region C (e.g., region C1) is located chronologically earlier than (orbefore) region A.

Since region C (e.g., region C1) is located further apart from the fieldsynchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion C (e.g., region C2 and region C3) located before region A, thereceiving system may use the channel information obtained from the lastknown data sequence to perform equalization. However, when the channelsare subject to fast and frequent changes, the equalization may not beperformed perfectly. Therefore, the equalization performance of region Cmay be deteriorated as compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor303 may encode the mobile service data, which are to be inserted to eachregion based upon the characteristic of each hierarchical region, at adifferent coding rate. For example, the block processor 303 may encodethe mobile service data, which are to be inserted in regions A1 to A5 ofregion A, at a coding rate of ½. Then, the group formatter 304 mayinsert the ½-rate encoded mobile service data to regions A1 to A5.

The block processor 303 may encode the mobile service data, which are tobe inserted in regions B1 and B2 of region B, at a coding rate of ¼having higher error correction ability as compared to the ½-coding rate.Then, the group formatter 304 inserts the ¼-rate coded mobile servicedata in region B1 and region B2. Furthermore, the block processor 303may encode the mobile service data, which are to be inserted in regionsC1 to C3 of region C, at a coding rate of ¼ or a coding rate havinghigher error correction ability than the ¼-coding rate. Then, the groupformatter 304 may either insert the encoded mobile service data toregions C1 to C3, as described above, or leave the data in a reservedregion for future usage.

In addition, the group formatter 304 also inserts supplemental data,such as signaling information that notifies the overall transmissioninformation, other than the mobile service data in the data group. Also,apart from the encoded mobile service data outputted from the blockprocessor 303, the group formatter 304 also inserts MPEG header placeholders, non-systematic RS parity place holders, main service data placeholders, which are related to data deinterleaving in a later process, asshown in FIG. 7A. Herein, the main service data place holders areinserted because the mobile service data bytes and the main service databytes are alternately mixed with one another in regions B and C basedupon the input of the data deinterleaver, as shown in FIG. 7A. Forexample, based upon the data outputted after data deinterleaving, theplace holder for the MPEG header may be allocated at the very beginningof each packet.

Furthermore, the group formatter 304 either inserts known data generatedin accordance with a pre-determined method or inserts known data placeholders for inserting the known data in a later process. Additionally,place holders for initializing the trellis encoding module 256 are alsoinserted in the corresponding regions.

For example, the initialization data place holders may be inserted inthe beginning of the known data sequence.

Herein, the size of the mobile service data that can be inserted in adata group may vary in accordance with the sizes of the trellisinitialization place holders or known data (or known data placeholders), MPEG header place holders, and RS parity place holders.

FIG. 8 illustrates a part of data region A of the signal frame shown inFIG. 7A. Various data symbol regions are shown FIG. 8. The top segmentis a field sync segment having a length of 832 symbols. The known dataare included in first, second, and third known data areas as shown inFIG. 8. The first known data area is located 16 segments below the fieldsync signal (top segment in FIG. 8). The second known data area islocated 16 segments below the first known data area, and the third knowndata area is located 16 segments below the second known data area.

Each of the first, second, and third known data areas includes aninitialization data region including data (4 symbols) required toinitialize trellis decoding. Furthermore, each of the first and secondknown data regions further includes a dummy data region next to theinitialization data region, and a known data region next to the dummydata region. The known data region includes known data symbols which maybe used to compensate channel distortion of a channel equalizer or totransmit an error correction coding mode. In addition, they can be usedfor initial carrier recovery. The dummy data region includes dummy knowndata symbols which can be combined with the known data symbols in theknown data region to form a total of 1424 known data symbols requiredfor trellis decoding.

The known data region (1424 symbols) included in the first known dataarea may include a training sequence which can be used to obtain achannel impulse response (CIR) required for channel equalization. Thefirst known data region further includes a reserved data region (252symbols) which may be used to transmit an error correction code mode.For example, the reserved data region may include informationidentifying a Serial Concatenated Convolution Code (SCCC) mode which isan example of the error correction code mode. Table 1 below shows anexample of the SCCC mode. Herein, the mode designating the coding rateof each region will be referred to as a serial concatenated convolutioncode (SCCC) mode for simplicity. Examples of the SCCC mode are shown inTable 1 below.

TABLE 1 SCCC 

 (code rate) SCCC 

Region A Region B Region C 0 1/2 1/2 1/2 1 1/2 1/2 1/4 2 1/2 1/4 1/2 31/2 1/4 1/4 4 1/4 1/4 1/2 5 1/4 1/4 1/4

For example, when the SCCC mode value that is extracted from the knowndata region is equal to ‘2’, this indicates that region A and region Cwithin the corresponding data group are encoded at a coding rate of ½and that region B is encoded at a coding rate of ¼. The transmittingsystem of the present invention generates 6 patterns corresponding toeach mode value shown in Table 1 based upon an agreement between thetransmitting system and the receiving system. Herein, the correspondingpattern may be inserted in the known data region for each data group. Inthis case, the receiving system may obtain the SCCC mode informationfrom the known data region prior to performing a decoding process inaccordance with the corresponding SCCC mode.

If such identification information is included, the broadcast receivingsystem may use the identified SCCC mode during SCCC decoding. The firstknown data region further includes two 576-symbol ACQ data regionsincluding data required to acquire initial carrier frequencysynchronization. And, the ACQ data regions can be further used toacquire synchronization for mobile service data.

Referring back to FIG. 8, the second known data area located 32 segmentsbelow the field sync segment includes an initialization data regionincluding data required to initialize trellis decoding, a dummy dataregion, and a known data region including known data to be used forchannel equalization. Similarly, the third known data area includes aninitialization data region including data required to initialize trellisdecoding, and a known data region including known data to be used forchannel equalization. A part of the initialization data region may beused to estimate a channel impulse response (CIR) as shown in FIG. 8 inwhich a start of CIR TS is located in the initialization data region.

The data region between the field sync segment and the first known dataregion includes 11892 valid data symbols, the data region between thefirst and second known data regions includes 10480 valid data symbols,and the data region between the second and third known data regionsincludes 11888 valid data symbols. The size of each data region shown inFIG. 8 can be altered. The known data can be used for channelequalization, or they can be used for transmit various signalinginformation. The field sync segment can also include signalinginformation.

FIGS. 9( a) to 9(c) illustrate a data structure (arrangement) oftransmission (Tx) parameters included in a mobile service data region assignaling data. FIG. 9( a) illustrates signaling data having a length of4 bytes. The signaling data include various information specifying aservice identifier (ID), an RS mode for regions A and B shown in FIG.7A, an RS mode for region C shown in FIG. 7A, a super frame size (SFS),a permuted frame index (PFI) indicating a location of an RS frame in asuper frame, a burst size, a group index (GI) indicating an index of adata group, and a time to a next burst (TNB). The sizes of theseinformation are shown in FIG. 9( a). FIGS. 9( b) and 9(c) illustratearrangements of the signaling data in the signal frame shown in FIG. 7A.If an error correction mode for region A in the signal frame is a ½ rateSCCC mode (hereinafter, error correction mode 1), region A may include afirst data region having 4-byte signaling data, a second data regionhaving 4-byte duplicated signaling data, and a third data region having32-byte RS parity data, as shown in FIG. 9( b). Alternatively, if theerror correction mode for region A is a ¼ rate SCCC mode (hereinafter,error correction mode 2), region A may include a first data regionhaving 4-byte signaling data and a second data region having 16-byte RSparity data.

FIG. 10 illustrates how the signaling data are inserted in a signalframe after interleaving in the broadcast transmitting system. Thesignaling data may be multiplexed with mobile service data in region A.Referring to FIG. 10, region A is divided into sub-regions A1 to A5 byeach known data region, where sub-regions A1 to A5 are positioned fromtop to bottom. If mobile service data including the 32-byte data shownin FIG. 9( b) are encoded in error correction mode 1 (½ rate) andinterleaved, 6, 8, 6, 6, and 6 bytes of the 32-byte data are included insub-regions A1, A2, A3, A4, and A5, respectively, as shown in FIG. 10.On the other hand, if mobile service data including the 16-byte datashown in FIG. 9( c) are encoded in error correction mode 2 (¼ rate), 3,4, 3, 3, and 3 bytes of the 16-byte data are inserted in sub-regions A1,A2, A3, A4, and A5, respectively.

A broadcast receiving system can obtain the transmission parameters fromthe mobile service data by protocol with a broadcast transmittingsystem. Using the transmission parameters, the receiving system canidentify a SCCC mode before performing SCCC decoding and use theidentified SCCC mode during error correction decoding. The signalingdata can be included in at least one of a field sync region, a knowndata region, and a mobile service data region, and the signaling datacan include various transmission parameters.

The output of the group formatter 304 is inputted to the datadeinterleaver 305. And, the data deinterleaver 305 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 306. More specifically, when the data and place holderswithin the data group configured, as shown in FIG. 7A, are deinterleavedby the data deinterleaver 305, the data group being outputted to thepacket formatter 306 is configured to have the structure shown in FIG.7B.

The packet formatter 306 removes the main service data place holders andthe RS parity place holders that were allocated for the deinterleavingprocess from the deinterleaved data being inputted. Then, the packetformatter 306 groups the remaining portion and replaces the 4-byte MPEGheader place holder with an MPEG header having a null packet PID (or anunused PID from the main service data packet). Also, when the groupformatter 304 inserts known data place holders, the packet formatter 306may insert actual known data in the known data place holders, or maydirectly output the known data place holders without any modification inorder to make replacement insertion in a later process. Thereafter, thepacket formatter 306 identifies the data within the packet-formatteddata group, as described above, as a 188-byte unit mobile service datapacket (i.e., MPEG TS packet), which is then provided to the packetmultiplexer 240.

The packet multiplexer 240 multiplexes the mobile service data packetoutputted from the pre-processor 230 and the main service data packetoutputted from the packet jitter mitigator 220 in accordance with apre-defined multiplexing method. Then, the packet multiplexer 240outputs the multiplexed data packets to the data randomizer 251 of thepost-processor 250. Herein, the multiplexing method may vary inaccordance with various variables of the system design. One of themultiplexing methods of the packet formatter 240 consists of providing aburst section along a time axis, and, then, transmitting a plurality ofdata groups during a burst-on section within the burst section, andtransmitting only the main service data during the burst-off sectionwithin the burst section. Herein, the burst section indicates thesection starting from the beginning of the current burst until thebeginning of the next burst.

At this point, the main service data may be transmitted during theburst-on section. The packet multiplexer 240 refers to the transmissionparameter, such as information on the burst size or the burst period, soas to be informed of the number of data groups and the period of thedata groups included in a single burst. Herein, the mobile service dataand the main service data may co-exist in the burst-on section, and onlythe main service data may exist in the burst-off section. Therefore, amain data service section transmitting the main service data may existin both burst-on and burst-off sections. At this point, the main dataservice section within the burst-on section and the number of main dataservice packets included in the burst-off section may either bedifferent from one another or be the same.

When the mobile service data are transmitted in a burst structure, inthe receiving system receiving only the mobile service data turns thepower on only during the burst section, thereby receiving thecorresponding data. Alternatively, in the section transmitting only themain service data, the power is turned off so that the main service dataare not received in this section. Thus, the power consumption of thereceiving system may be reduced.

FIG. 11 illustrates an example of acquiring mobile service data includedin a particular data group within a burst according to the presentinvention. For simplicity, it will be assumed that the mobile servicedata of FIG. 11 include a program associated with a particular service.Depending upon the data group, mobile service data and main service datamay be multiplexed in a single burst. When the mobile service data groupis included and transmitted in a group being included in a burst, thebroadcast receiving system turns the power on only during the burst thatis included in a burst so as to receive a broadcast signal (i.e.,on-time). Also, the broadcast receiving system may decode and output themobile service data included in the data group within the burst that isbeing received. Furthermore, the broadcast receiving system may obtain atime to a next burst (TNB) from the signaling information. Then, byturning the power off until the next burst is received, the broadcastreceiving system does not receive any broadcast signal (i.e., off-time).The broadcast receiving system turns the power back on during the nextburst (burst 2), thereby receiving the mobile service data included inthe newly received burst (i.e., on-time).

FIG. 12 illustrates an example of mobile service data associated to aplurality of services within one burst being multiplexed. Referring toFIG. 12, the mobile service data providing a first service will beindicated as mo1, and the mobile service data providing a second servicewill be indicated as mo2. In this example, a burst represents a signalsection (or block) wherein the mobile service data are multiplexed. Morespecifically, the signal block including the mobile service dataassociated to the first service may become a first burst section, andthe signal block including the mobile service data associated to thesecond service may become a second burst section. When the broadcastreceiving system wishes to receive the program associated to the firstservice, a data block including data groups G1 and G3 in which the datacorresponding to the first service is determined as the burst section.Thus, the power is turned on during the burst section. The broadcastreceiving system obtains the next burst in which the data groupcorresponding to the first service from the signaling informationindicated as TNB_(G1) and TNB_(G2). Therefore, the power is turned offuntil the next burst. Then, the power is turned back on at the point thenext burst is being received.

Alternatively, when the broadcast receiving system wishes to receive theprogram associated to the second service, the power may be turned on andoff only during the burst section corresponding to a signal sectionincluding the data on the second service. More specifically, the poweris turned on during the burst section having the data groupcorresponding to the second service included therein. Then, thebroadcast receiving system obtains the next burst in which the datagroup corresponding to the second service from the signaling informationindicated as TNB_(G2) and TNB_(G4). Therefore, the power is turned offuntil the next burst. Then, the power is turned back on at the point thenext burst is being received.

Detailed Embodiments of the RS Frame Structure and Packet Multiplexing

Hereinafter, detailed embodiments of the pre-processor 230 and thepacket multiplexer 240 will now be described. According to an embodimentof the present invention, the N value corresponding to the length of arow, which is included in the RS frame that is configured by the RSframe encoder 302, is set to 538. Accordingly, the RS frame encoder 302receives 538 transport stream (TS) packets so as to configure a first RSframe having the size of 538*187 bytes. Thereafter, as described above,the first RS frame is processed with a (235,187)-RS encoding process soas to configure a second RS frame having the size of 538*235 bytes.Finally, the second RS frame is processed with generating a 16-bitchecksum so as to configure a third RS frame having the sizes of540*235.

Meanwhile, as shown in FIG. 7A, the sum of the number of bytes ofregions A1 to A5 of region A, in which ½-rate encoded mobile servicedata are to be inserted, among the plurality of regions within the datagroup is equal to 13024 bytes (=2428+2580+2772+2472+2772 bytes). Herein,the number of byte prior to performing the ½-rate encoding process isequal to 6512 (=13024/2). On the other hand, the sum of the number ofbytes of regions B1 and B2 of region B, in which ¼-rate encoded mobileservice data are to be inserted, among the plurality of regions withinthe data group is equal to 2280 bytes (=930+1350 bytes). Herein, thenumber of byte prior to performing the ¼-rate encoding process is equalto 570 (=2280/4).

In other words, when 7082 bytes of mobile service data are inputted tothe block processor 303, 6512 byte are expanded to 13024 bytes by being½-rate encoded, and 570 bytes are expanded to 2280 bytes by being ¼-rateencoded. Thereafter, the block processor 303 inserts the mobile servicedata expanded to 13024 bytes in regions A1 to A5 of region A and, also,inserts the mobile service data expanded to 2280 bytes in regions B1 andB2 of region B. Herein, the 7082 bytes of mobile service data beinginputted to the block processor 303 may be divided into an output of theRS frame encoder 302 and signaling information. In the presentinvention, among the 7082 bytes of mobile service data, 7050 bytescorrespond to the output of the RS frame encoder 302, and the remaining32 bytes correspond to the signaling information data. Then, ½-rateencoding or ¼-rate encoding is performed on the corresponding databytes.

Meanwhile, a RS frame being processed with RS encoding and CRC encodingfrom the RS frame encoder 302 is configured of 540*235 bytes, in otherwords, 126900 bytes. The 126900 bytes are divided by 7050-byte unitsalong the time axis, so as to produce 18 7050-byte units. Thereafter, a32-byte unit of signaling information data is added to the 7050-byteunit mobile service data being outputted from the RS frame encoder 302.Subsequently, the RS frame encoder 302 performs ½-rate encoding or¼-rate encoding on the corresponding data bytes, which are thenoutputted to the group formatter 304. Accordingly, the group formatter304 inserts the ½-rate encoded data in region A and the ¼-rate encodeddata in region B.

The process of deciding an N value that is required for configuring theRS frame from the RS frame encoder 302 will now be described in detail.More specifically, the size of the final RS frame (i.e., the third RSframe), which is RS encoded and CRC encoded from the RS frame encoder302, which corresponds to (N+2)*235 bytes should be allocated to Xnumber of groups, wherein X is an integer. Herein, in a single datagroup, 7050 data bytes prior to being encoded are allocated. Therefore,if the (N+2)*235 bytes are set to be the exact multiple of 7050(=30*235), the output data of the RS frame encoder 302 may beefficiently allocated to the data group. According to an embodiment ofthe present invention, the value of N is decided so that (N+2) becomes amultiple of 30. For example, in the present invention, N is equal to538, and (N+2)(=540) divided by 30 is equal to 18. This indicates thatthe mobile service data within one RS frame are processed with either½-rate encoding or ¼-rate encoding. The encoded mobile service data arethen allocated to 18 data groups.

FIG. 13 illustrates a process of dividing the RS frame according to thepresent invention. More specifically, the RS frame having the size of(N+2)*235 is divided into 30*235 byte blocks. Then, the divided blocksare mapped to a single group. In other words, the data of a block havingthe size of 30*235 bytes are processed with one of a ½-rate encodingprocess and a ¼-rate encoding process and are, then, inserted in a datagroup.

In another example, it is assumed that the mobile service data that areto be inserted in region C are ½-rate encoded by the block processor303, and that the mobile service data that are to be inserted in regionC correspond to a different type of mobile service data that areinserted in regions A and B. In this case, as shown in FIG. 7A, thetotal number of ½-rate encoded mobile service data bytes that are to beincluded in regions C1 to C3 of region C is equal to 4144 bytes (i.e.,4144=1272+1560+1312). In this case, the total number of mobile servicedata bytes prior to being ½-rate encoded is equal to 2072 bytes (i.e.,2072=4144/2). At this point, when it is assumed that 18 data groups aregrouped to form a RS frame, and that the mobile service data of the RSframe are inserted into the region C, the RS frame is configured of37296 bytes. Herein, the number of RS parity bytes P is set to be equalto 36 (i.e., P=36), and 2 CRC checksums are set to be included for eachrow.

Accordingly, a total of 165 188-byte mobile service data packets may betransmitted for each RS frame. In this case, 55 bytes may remain foreach RS frame of the region C within the data group. Remaining databytes may occur, when dividing each RS frame into a plurality of datagroups having the same size. More specifically, remaining data bytes mayoccur in particular regions in each RS frame depending upon the size ofthe RS frames, the size and number of divided data groups, the number ofmobile service data bytes that may be inserted into each data group, thecoding rate of the corresponding region, the number of RS parity bytes,whether or not a CRC checksum has been allocated, and, if any, thenumber of CRC checksums allocated.

When dividing the RS frame into a plurality of data groups having thesame size, and when remaining data bytes occur in the corresponding RSframe, K number of dummy bytes are added to the corresponding RS frame,wherein K is equal to the number of remaining data bytes within the RSframe. Then, the dummy byte-added RS frame is divided into a pluralityof data groups. This process is illustrated in FIG. 14. Morespecifically, FIG. 14 illustrates an example of processing K number ofremaining data bytes, which are produced by dividing the RS frame havingthe size of (N+2)*(187+P) bytes into M number of data groups havingequal sizes. In this case, as shown in FIG. 14( a), K number of dummybytes are added to the RS frame having the size of (N+2)*(187+P) bytes.Subsequently, the RS frame is read in row units, thereby being dividedinto M number of data groups, as shown in FIG. 14( b). At this point,each data group has the size of NoBytesPerGrp bytes. This may bedescribed by Equation 3 shown below.

M×NoBytesPerGrp=(N+2)×(187+P)×K  Equation 3

Herein, NoBytesPerGrp indicates the number of bytes allocated for eachgroup (i.e., the Number of Bytes Per Group). More specifically, the sizecorresponding to the number of byte in one RS frame+K bytes is equal tothe size of the M number of data groups.

When the mobile service data are transmitted by using theabove-described method and transmission mode, the data randomizer 301 ofthe pre-processor 230 may receive the mobile service data packetsthrough a first mobile service data path and a second mobile servicedata path, to which data that are to be allocated to regions A and B areinputted. More specifically, 538 data packets are inputted to the firstmobile service data path, and 165 data packets are inputted to thesecond mobile service data path. In order to do so, a plurality of datarandomizers and RS frame encoders may be provided. Accordingly, the 538data packets being inputted to the first mobile service data path andthe 165 data packets being inputted to the second mobile service datapath are randomized by each respective data randomizer. Then, each RSframe encoder performs RS frame unit encoding and super frame unit rowpermutation processes on the inputted data packets. Thereafter, theprocessed data packets are divided back to RS frame units, thereby beinginputted to the block processor 303.

For example, the RS frame encoder encoding the data being inputtedthrough the first mobile service data path adds 48 parity bytes in acolumn direction to the corresponding RS frame. This RS frame encoderalso adds a 2-byte CRC checksum in a row direction to the correspondingRS frame. The RS frame encoder encoding the data being inputted throughthe second mobile service data path adds 36 parity bytes in a columndirection to the corresponding RS frame. This RS frame encoder also addsa 2-byte CRC checksum in a row direction to the corresponding RS frame.

The block processor 303 performs ½-rate encoding on the data that are tobe allocated to regions A and C. And, the block processor 303 performs¼-rate encoding on the data that are to be allocated to region B. Theblock processor 303 then outputs the encoded data to the group formatter304.

At this point, since 55 bytes remain in region C included in the datagroup for each RS frame, as described above, the block processor 303adds 55 bytes of dummy bytes to region C, once all data that are to beallocated to region C are inputted. Thereafter, the block processor 303½-rate encodes the processed data. Herein, the dummy bytes may be addedby the block processor 303, as described above, or may be added by anexternal block (not shown).

The group formatter 304 inserts (or allocates) the ½-rate or ¼-rateencoded and inputted mobile service data and known data (e.g., MPEGheader place holders, non-systematic RS parity place holders,initialization data place holders, etc.) to the respective regionswithin the data group shown in FIG. 7A. For example, the mobile servicedata that are inputted through the first mobile service data path andthen ½-rate or ¼-rate encoded are inserted in regions A and B. And, themobile service data that are inputted through the second mobile servicedata path and then ½-rate encoded are inserted in region C.

FIG. 15 illustrates detailed exemplary operations of the packetmultiplexer 240 according to an embodiment of the present invention.More specifically, the packet multiplexer 240 multiplexes data fieldsincluding a data group and data fields only including main service dataand outputs the randomized data to the data randomizer 251. According tothe present invention, the data fields including a data group aretransmitted to a burst-on section. And, the data fields including onlythe main service data are transmitted to a burst-off section. At thispoint, the burst-on section may also transmit the main service data.

FIG. 15 illustrates exemplary operations of a packet multiplexer fortransmitting the data group according to the present invention. Morespecifically, the packet multiplexer 240 multiplexes a field including adata group, in which the mobile service data and main service data aremixed with one another, and a field including only the main servicedata. Thereafter, the packet multiplexer 240 outputs the multiplexedfields to the data randomizer 251. At this point, in order to transmitthe RS frame having the size of 540*235 bytes, 18 data groups should betransmitted. Herein, each data group includes field synchronizationdata, as shown in FIG. 7A. Therefore, the 18 data groups are transmittedduring 18 field sections, and the section during which the 18 datagroups are being transmitted corresponds to the burst-on section.

In each field within the burst-on section, a data group including fieldsynchronization data is multiplexed with main service data, which arethen outputted. For example, in the embodiment of the present invention,in each field within the burst-on section, a data group having the sizeof 118 segments is multiplexed with a set of main service data havingthe size of 194 segments. Referring to FIG. 15, during the burst-onsection (i.e., during the 18 field sections), a field including 18 datagroups is transmitted. Then, during the burst-off section that follows(i.e., during the 12 field sections), a field consisting only of themain service data is transmitted. Subsequently, during a subsequentburst-on section, 18 fields including 18 data groups are transmitted.And, during the following burst-off section, 12 fields consisting onlyof the main service data are transmitted.

Furthermore, in the present invention, the same type of data service maybe provided in the first burst-on section including the first 18 datagroups and in the second burst-on section including the next 18 datagroups. Alternatively, different types of data service may be providedin each burst-on section. For example, when it is assumed that differentdata service types are provided to each of the first burst-on sectionand the second burst-on section, and that the receiving system wishes toreceive only one type of data service, the receiving system turns thepower on only during the corresponding burst-on section including thedesired data service type so as to receive the corresponding 18 datafields. Then, the receiving system turns the power off during theremaining 42 field sections so as to prevent other data service typesfrom being received. Thus, the amount of power consumption of thereceiving system may be reduced. In addition, the receiving systemaccording to the present invention is advantageous in that one RS framemay be configured from the 18 data groups that are received during asingle burst-on section.

According to the present invention, the number of data groups includedin a burst-on section may vary based upon the size of the RS frame, andthe size of the RS frame varies in accordance with the value N. Morespecifically, by adjusting the value N, the number of data groups withinthe burst section may be adjusted. Herein, in an example of the presentinvention, the (235,187)-RS encoding process adjusts the value N duringa fixed state. Furthermore, the size of the mobile service data that canbe inserted in the data group may vary based upon the sizes of thetrellis initialization data or known data, the MPEG header, and the RSparity, which are inserted in the corresponding data group.

Meanwhile, since a data group including mobile service data in-betweenthe data bytes of the main service data during the packet multiplexingprocess, the shifting of the chronological position (or place) of themain service data packet becomes relative. Also, a system object decoder(i.e., MPEG decoder) for processing the main service data of thereceiving system, receives and decodes only the main service data andrecognizes the mobile service data packet as a null data packet.Therefore, when the system object decoder of the receiving systemreceives a main service data packet that is multiplexed with the datagroup, a packet jitter occurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 240 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data is relatively small, thepacket jitter may cause considerable problem. More specifically, due tothe packet jitter, an overflow or underflow may occur in the buffer forthe main service data of the receiving system (e.g., the buffer for theaudio data). Therefore, the packet jitter mitigator 220 re-adjusts therelative position of the main service data packet so that the overflowor underflow does not occur in the system object decoder.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The packet jitter mitigator 220 repositions the audio datapackets in the main service data section so that the audio data packetsof the main service data can be as equally and uniformly aligned andpositioned as possible. The standard for repositioning the audio datapackets in the main service data performed by the packet jittermitigator 220 will now be described. Herein, it is assumed that thepacket jitter mitigator 220 knows the same multiplexing information asthat of the packet multiplexer 240, which is placed further behind thepacket jitter mitigator 220.

Firstly, if one audio data packet exists in the main service datasection (e.g., the main service data section positioned between two datagroups) within the burst-on section, the audio data packet is positionedat the very beginning of the main service data section. Alternatively,if two audio data packets exist in the corresponding data section, oneaudio data packet is positioned at the very beginning and the otheraudio data packet is positioned at the very end of the main service datasection. Further, if more than three audio data packets exist, one audiodata packet is positioned at the very beginning of the main service datasection, another is positioned at the very end of the main service datasection, and the remaining audio data packets are equally positionedbetween the first and last audio data packets. Secondly, during the mainservice data section placed immediately before the beginning of aburst-on section (i.e., during a burst-off section), the audio datapacket is placed at the very end of the corresponding section.

Thirdly, during a main service data section within the burst-off sectionafter the burst-on section, the audio data packet is positioned at thevery end of the main service data section. Finally, the data packetsother than audio data packets are positioned in accordance with theinputted order in vacant spaces (i.e., spaces that are not designatedfor the audio data packets). Meanwhile, when the positions of the mainservice data packets are relatively re-adjusted, associated programclock reference (PCR) values may also be modified accordingly. The PCRvalue corresponds to a time reference value for synchronizing the timeof the MPEG decoder. Herein, the PCR value is inserted in a specificregion of a TS packet and then transmitted.

In the example of the present invention, the packet jitter mitigator 220also performs the operation of modifying the PCR value. The output ofthe packet jitter mitigator 220 is inputted to the packet multiplexer240. As described above, the packet multiplexer 240 multiplexes the mainservice data packet outputted from the packet jitter mitigator 220 withthe mobile service data packet outputted from the pre-processor 230 intoa burst structure in accordance with a pre-determined multiplexing rule.Then, the packet multiplexer 240 outputs the multiplexed data packets tothe data randomizer 251 of the post-processor 250.

If the inputted data correspond to the main service data packet, thedata randomizer 251 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 251. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 252.

On the other hand, if the inputted data correspond to the mobile servicedata packet, the data randomizer 251 may randomize only a portion of thedata packet. For example, if it is assumed that a randomizing processhas already been performed in advance on the mobile service data packetby the pre-processor 230, the data randomizer 251 deletes thesynchronization byte from the 4-byte MPEG header included in the mobileservice data packet and, then, performs the randomizing process only onthe remaining 3 data bytes of the MPEG header. Thereafter, therandomized data bytes are outputted to the RS encoder/non-systematic RSencoder 252. More specifically, the randomizing process is not performedon the remaining portion of the mobile service data excluding the MPEGheader. In other words, the remaining portion of the mobile service datapacket is directly outputted to the RS encoder/non-systematic RS encoder252 without being randomized. Also, the data randomizer 251 may or maynot perform a randomizing process on the known data (or known data placeholders) and the initialization data place holders included in themobile service data packet.

The RS encoder/non-systematic RS encoder 252 performs an RS encodingprocess on the data being randomized by the data randomizer 251 or onthe data bypassing the data randomizer 251, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 253. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 252performs the same systematic RS encoding process as that of theconventional broadcasting system, thereby adding the 20-byte RS paritydata at the end of the 187-byte data. Alternatively, if the inputteddata correspond to the mobile service data packet, the RSencoder/non-systematic RS encoder 252 performs a non-systematic RSencoding process. At this point, the 20-byte RS parity data obtainedfrom the non-systematic RS encoding process are inserted in apre-decided parity byte place within the mobile service data packet.

The data interleaver 253 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 253 is inputted to theparity replacer 254 and to the non-systematic RS encoder 255. Meanwhile,a process of initializing a memory within the trellis encoding module256 is primarily required in order to decide the output data of thetrellis encoding module 256, which is located after the parity replacer254, as the known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoding module 256 should first be initializedbefore the received known data sequence is trellis-encoded. At thispoint, the beginning portion of the known data sequence that is receivedcorresponds to the initialization data place holder and not to theactual known data. Herein, the initialization data place holder has beenincluded in the data by the group formatter within the pre-processor 230in an earlier process. Therefore, the process of generatinginitialization data and replacing the initialization data place holderof the corresponding memory with the generated initialization data arerequired to be performed immediately before the inputted known datasequence is trellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encodingmodule 256. Further, due to the newly replaced initialization data, aprocess of newly calculating the RS parity and replacing the RS parity,which is outputted from the data interleaver 253, with the newlycalculated RS parity is required. Therefore, the non-systematic RSencoder 255 receives the mobile service data packet including theinitialization data place holders, which are to be replaced with theactual initialization data, from the data interleaver 253 and alsoreceives the initialization data from the trellis encoding module 256.

Among the inputted mobile service data packet, the initialization dataplace holders are replaced with the initialization data, and the RSparity data that are added to the mobile service data packet are removedand processed with non-systematic RS encoding. Thereafter, the new RSparity obtained by performing the non-systematic RS encoding process isoutputted to the parity replacer 255. Accordingly, the parity replacer255 selects the output of the data interleaver 253 as the data withinthe mobile service data packet, and the parity replacer 255 selects theoutput of the non-systematic RS encoder 255 as the RS parity. Theselected data are then outputted to the trellis encoding module 256.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization dataplace holders that are to be replaced, is inputted, the parity replacer254 selects the data and RS parity that are outputted from the datainterleaver 253. Then, the parity replacer 254 directly outputs theselected data to the trellis encoding module 256 without anymodification. The trellis encoding module 256 converts the byte-unitdata to symbol units and performs a 12-way interleaving process so as totrellis-encode the received data. Thereafter, the processed data areoutputted to the synchronization multiplexer 260.

The synchronization multiplexer 260 inserts a field synchronizationsignal and a segment synchronization signal to the data outputted fromthe trellis encoding module 256 and, then, outputs the processed data tothe pilot inserter 271 of the transmission unit 270. Herein, the datahaving a pilot inserted therein by the pilot inserter 271 are modulatedby the modulator 272 in accordance with a pre-determined modulatingmethod (e.g., a VSB method). Thereafter, the modulated data aretransmitted to each receiving system though the radio frequency (RF)up-converter 273.

Block Processor

FIG. 16 illustrates a block diagram showing a structure of a blockprocessor according to the present invention. Herein, the blockprocessor includes a byte-bit converter 401, a symbol encoder 402, asymbol interleaver 403, and a symbol-byte converter 404. The byte-bitconverter 401 divides the mobile service data bytes that are inputtedfrom the RS frame encoder 112 into bits, which are then outputted to thesymbol encoder 402. The byte-bit converter 401 may also receivesignaling information including transmission parameters. The signalinginformation data bytes are also divided into bits so as to be outputtedto the symbol encoder 402. Herein, the signaling information includingtransmission parameters may be processed with the same data processingstep as that of the mobile service data. More specifically, thesignaling information may be inputted to the block processor 303 bypassing through the data randomizer 301 and the RS frame encoder 302.Alternatively, the signaling information may also be directly outputtedto the block processor 303 without passing though the data randomizer301 and the RS frame encoder 302.

The symbol encoder 402 corresponds to a D/E-rate encoder encoding theinputted data from G bits to H bits and outputting the data encoded atthe coding rate of D/E. According to the embodiment of the presentinvention, it is assumed that the symbol encoder 402 performs either acoding rate of ½ (also referred to as a ½-rate encoding process) or anencoding process at a coding rate of ¼ (also referred to as a ¼-rateencoding process). The symbol encoder 402 performs one of ½-rateencoding and ¼-rate encoding on the inputted mobile service data andsignaling information. Thereafter, the signaling information is alsorecognized as the mobile service data and processed accordingly.

In case of performing the ½-rate coding process, the symbol encoder 402receives 1 bit and encodes the received 1 bit to 2 bits (i.e., 1symbol). Then, the symbol encoder 402 outputs the processed 2 bits (or 1symbol). On the other hand, in case of performing the ¼-rate encodingprocess, the symbol encoder 402 receives 1 bit and encodes the received1 bit to 4 bits (i.e., 2 symbols). Then, the symbol encoder 402 outputsthe processed 4 bits (or 2 symbols).

The symbol encoder 402 may be operated as an encoder having the codingrate of ½ or may be operated as an encoder having the coding rate of ¼.

FIG. 17A to FIG. 17C illustrate block views showing exemplary operationsof the symbol encoder having the coding rate of ¼ according to anembodiment of the present invention. The symbol encoder of FIG. 17Aincludes a ¼ outer encoder 411, and a parallel/serial converter 412.Referring to FIG. 17A, the ¼ outer encoder 411 encodes a mobile servicedata bit U, which is being inputted to the ¼ outer encoder 411, to u0 tou3 (i.e., to 2 symbols). Then, the ¼ outer encoder 411 outputs theencoded 2 symbols to the parallel/serial converter 412. Theparallel/serial converter 412 converts the two inputted symbols toserial symbol units, which are then serially outputted to the symbolinterleaver 403. More specifically, the parallel/serial converter 412outputs one symbol, which is configured of u0 and u1, to the symbolinterleaver 403. And, then the parallel/serial converter 412 outputsanother symbol, which is configured of u2 and u3, to the symbolinterleaver 403.

The symbol encoder of FIG. 17B includes a ½ outer encoder 421 and arepeater 422. Referring to FIG. 17B, the ½ outer encoder 421 encodes amobile service data bit U, which is being inputted to the ½ outerencoder 421, to u0 and u1 (i.e., to 1 symbol). Then, the ½ outer encoder421 outputs the encoded symbol to the repeater 422. The repeater 422repeats the ½-rate encoded symbol one time and outputs the repeatedsymbol to the symbol interleaver 403. More specifically, the repeater422 outputs the symbol configured of bit u0 and bit u1 to the symbolinterleaver 403. Then, the repeater 422 outputs the symbol configured ofbit u0 and bit u1 once again to the symbol interleaver 403.

The symbol encoder of FIG. 17C includes a repeater 431 and a ½ outerencoder 432. Referring to FIG. 17C, the repeater 431 repeats a mobileservice data bit U, which is being inputted to the repeater 431, so asto output two bits U and U to the ½ outer encoder 432. Thereafter, the ½outer encoder 432 encodes the mobile service data bit U being outputtedfrom the repeater 431, to u0 and u1 (i.e., to 1 symbol). Then, the ½outer encoder 431 outputs the encoded symbol to the symbol interleaver403. At this point, since identical mobile service data bits U aresequentially inputted to the ½ outer encoder 432 twice, the ½ outerencoder 432 performs the ½-rate encoding process twice on the mobileservice data bit U, which is being inputted to the repeater 431.

More specifically, when the symbol encoder 402 repeatedly outputs 2symbols encoded at a coding rate of ½, as shown in FIG. 17B, or when thesymbol encoder 402 performs the ½-rate encoding process two times on theinput data bit and then outputs the encoded data bit, as shown in FIG.17C, the overall coding rate becomes ¼. As described above, when thesymbol encoder 402 is operated as an encoder having a coding rate of ¼,the input data bit may be encoded at a coding rate of ¼, so that eachsymbol can be sequentially outputted one by one. Alternatively, theinput data may be encoded at a coding rate of ½ and then repeated onetime, so that each symbol can be sequentially outputted one by one.Furthermore, the input data bit may be encoded at a coding rate of ½ twotimes, so that each symbol can be sequentially outputted one by one.

Meanwhile, when the symbol encoder 402 is operated as an encoder havinga coding rate of ½, the input data bit is encoded at a coding rate of ½by the ½ outer encoder and then outputted. Alternatively, the input databit may also be encoded at a coding rate of ¼ by the ¼ outer encoder.Thereafter, when only one of the two symbols is selected and outputted,the symbol encoder 402 may be operated as an encoder having the codingrate of ½. In the description of the present invention, the ½-codingrate and the ¼-coding rate are merely exemplary, and the coding rate mayvary depending upon the selection of the encoded symbols or the numberof repetition of the symbols. Therefore, the present invention will notbe limited only to the examples given in the embodiments of the presentinvention. Nevertheless, if the coding rate is low, the actual amount ofdata that can be transmitted becomes smaller, accordingly. Therefore,these two factors should be accounted for when deciding the coding rate.

FIG. 18A illustrates a detailed block view of a ½ outer encoderaccording to an embodiment of the present invention. Referring to FIG.18A, the ½ outer encoder includes two delays (or a first delay and asecond delay) 501 and 503, and one adder 502. Herein, the ½ outerencoder encodes the input data bit U, so that 2 bits (i.e., u0 and u1)can be outputted. At this point, the input data bit U corresponds to anupper bit u0, which is outputted without modification and at the sametime encoded to be outputted as a lower bit u1. More specifically, theinput data bit U is directly outputted as the upper bit u0 withoutmodification and, simultaneously, outputted to the adder 502.

The adder 502 adds the input data bit U and the output of the firstdelay 501, which are then outputted to the second delay 503. Thereafter,the data that have been delayed by a set period of time (e.g., by 1clock) are outputted as the lower bit u1 and, at the same time, fed-backto the first delay 501. Subsequently, the first delay 501 delays datafed-back by from the second delay 503 by a set period of time (e.g., by1 clock). Then, the delayed data are outputted to the adder 502. At thispoint, if the data bit U being inputted to the symbol encoder 402corresponds to a data bit that is to be encoded at a coding rate of ¼, asymbol configured of u0u1 bits may be repeated twice and then outputted.Alternatively, the input data bit U may be repeated once, which is theninputted to the ½ outer encoder of FIG. 18A.

FIG. 18B illustrates a detailed block view of a ¼ outer encoderaccording to an embodiment of the present invention. Referring to FIG.18B, the ¼ outer encoder includes two delays (or a first delay and asecond delay) 501 and 503, and three adders 502, 504, and 505. Herein,the ¼ outer encoder encodes the input data bit U, so that 4 bits (i.e.,u0 to u3) can be outputted. At this point, the input data bit Ucorresponds to an uppermost bit u0, which is outputted withoutmodification and at the same time encoded to be outputted as lower bitu1u2u3. More specifically, the input data bit U is directly outputted asthe uppermost bit u0 and simultaneously outputted to the first and thirdadders 502 and 505. The first adder 502 adds the input data bit U andthe output bit of the first delay unit 501 and, then, outputs the addedbit to the second delay unit 503. Then, the data bit delayed by apre-determined time (e.g., by 1 clock) in the second delay unit 503 isoutputted as lower bit u1 and simultaneously fed-back to the first delayunit 501. The first delay unit 501 delays the data bit fed-back from thesecond delay unit 503 by a pre-determined time (e.g., by 1 clock). Then,the first delay unit 501 outputs the delayed data bit to the first adder502 and the second adder 504. The second adder 504 adds the data bitsoutputted from the first and second delay units 501 and 503 as a lowerbit u2. The third adder 505 adds the input data bit U and the output ofthe second delay unit 503 and outputs the added data bit as a lower bitu3.

At this point, if the input data bit U corresponds to data encoded at a½-coding rate, the symbol encoder 402 configures a symbol with u1u0 bitsfrom the 4 output bits u0u1u2u3. Then, the symbol encoder 402 outputsthe newly configured symbol. Alternatively, if the input data bit Ucorresponds to data encoded at a ¼-coding rate, the symbol encoder 402configures and outputs a symbol with bits u1u0 and, then, configures andoutputs another symbol with bits u2u3. According to another embodimentof the present invention, if the input data bit U corresponds to dataencoded at a ¼-coding rate, the symbol encoder 402 may also configureand output a symbol with bits u1u0, and then repeat the process onceagain and output the corresponding bits. According to yet anotherembodiment of the present invention, the symbol encoder outputs all fouroutput bits U u0u1u2u3. Then, when using the ½-coding rate, the symbolinterleaver 403 located behind the symbol encoder 402 selects only thesymbol configured of bits u1u0 from the four output bits u0u1u2u3.Alternatively, when using the ¼-coding rate, the symbol interleaver 403may select the symbol configured of bits u1u0 and then select anothersymbol configured of bits u2u3. According to another embodiment, whenusing the ¼-coding rate, the symbol interleaver 403 may repeatedlyselect the symbol configured of bits u1u0.

The output of the symbol encoder 402 is inputted to the symbolinterleaver 403. Then, the symbol interleaver 403 performs blockinterleaving in symbol units on the data outputted from the symbolencoder 402. Any interleaver performing structural rearrangement (orrealignment) may be applied as the symbol interleaver 403 of the blockprocessor. However, in the present invention, a variable length symbolinterleaver that can be applied even when a plurality of lengths isprovided for the symbol, so that its order may be rearranged, may alsobe used.

FIG. 19 illustrates a symbol interleaver according to an embodiment ofthe present invention. Herein, the symbol interleaver according to theembodiment of the present invention corresponds to a variable lengthsymbol interleaver that may be applied even when a plurality of lengthsis provided for the symbol, so that its order may be rearranged.Particularly, FIG. 19 illustrates an example of the symbol interleaverwhen BK=6 and BL=8. Herein, BK indicates a number of symbols that areoutputted for symbol interleaving from the symbol encoder 402. And, BLrepresents a number of symbols that are actually interleaved by thesymbol interleaver 403.

In the present invention, the symbol intereleaver 403 should satisfy theconditions of BL=2^(n) (wherein n is an integer) and of BL≧K. If thereis a difference in value between BK and BL, (BL−BK) number of null (ordummy) symbols is added, thereby creating an interleaving pattern.Therefore, BK becomes a block size of the actual symbols that areinputted to the symbol interleaver 403 in order to be interleaved. BLbecomes an interleaving unit when the interleaving process is performedby an interleaving pattern created from the symbol interleaver 403. Theexample of what is described above is illustrated in FIG. 19.

More specifically, FIG. 19( a) to FIG. 19( c) illustrate a variablelength interleaving process of a symbol interleaver. The number ofsymbols outputted from the symbol encoder 402 in order to be interleavedis equal to 6 (i.e., BK=6). In other words, 6 symbols are outputted fromthe symbol encoder 402 in order to be interleaved. And, the actualinterleaving unit (BL) is equal to 8 symbols. Therefore, as shown inFIG. 19( a), 2 symbols are added to the null (or dummy) symbol, therebycreating the interleaving pattern. Equation 4 shown below described theprocess of sequentially receiving BK number of symbols, the order ofwhich is to be rearranged, and obtaining an BL value satisfying theconditions of BL=2^(n) (wherein n is an integer) and of BL≧BK, therebycreating the interleaving so as to realign (or rearrange) the symbolorder.

In relation to all places, wherein 0≦i≦BL−1,

P(i)={S×i×(i+1)/2} mod BL  Equation 4

Herein, BL≧BK, BL=2^(n), and n and S are integers. Referring to FIG. 19,it is assumed that S is equal to 89, and that L is equal to 8, and FIG.19 illustrates the created interleaving pattern and an example of theinterleaving process. As shown in FIG. 19( b), the order of BK number ofinput symbols and (BL−BK) number of null symbols is rearranged by usingthe above-mentioned Equation 4. Then, as shown in FIG. 19( c), the nullbyte places are removed, so as to rearrange the order, by using Equation5 shown below. Thereafter, the symbol that is interleaved by therearranged order is then outputted to the symbol-byte converter.

if P(i)>BK−1, then P(i) place is removed and rearranged  Equation 5

Subsequently, the symbol-byte converter 404 converts to bytes the mobileservice data symbols, having the rearranging of the symbol ordercompleted and then outputted in accordance with the rearranged order,and thereafter outputs the converted bytes to the group formatter 304.

FIG. 20A illustrates a block diagram showing the structure of a blockprocessor according to another embodiment of the present invention.Herein, the block processor includes an interleaving unit 610 and ablock formatter 620. The interleaving unit 610 may include a byte-symbolconverter 611, a symbol-byte converter 612, a symbol interleaver 613,and a symbol-byte converter 614. Herein, the symbol interleaver 613 mayalso be referred to as a block interleaver.

The byte-symbol converter 611 of the interleaving unit 610 converts themobile service data X outputted in byte units from the RS frame encoder302 to symbol units. Then, the byte-symbol converter 611 outputs theconverted mobile service data symbols to the symbol-byte converter 612and the symbol interleaver 613. More specifically, the byte-symbolconverter 611 converts each 2 bits of the inputted mobile service databyte (=8 bits) to 1 symbol and outputs the converted symbols. This isbecause the input data of the trellis encoding module 256 consist ofsymbol units configured of 2 bits. The relationship between the blockprocessor 303 and the trellis encoding module 256 will be described indetail in a later process. At this point, the byte-symbol converter 611may also receive signaling information including transmissionparameters. Furthermore, the signaling information bytes may also bedivided into symbol units and then outputted to the symbol-byteconverter 612 and the symbol interleaver 613.

The symbol-byte converter 612 groups 4 symbols outputted from thebyte-symbol converter 611 so as to configure a byte. Thereafter, theconverted data bytes are outputted to the block formatter 620. Herein,each of the symbol-byte converter 612 and the byte-symbol converter 611respectively performs an inverse process on one another. Therefore, theyield of these two blocks is offset. Accordingly, as shown in FIG. 20B,the input data X bypass the byte-symbol converter 611 and thesymbol-byte converter 612 and are directly inputted to the blockformatter 620. More specifically, the interleaving unit 610 of FIG. 20Bhas a structure equivalent to that of the interleaving unit shown inFIG. 20A. Therefore, the same reference numerals will be used in FIG.20A and FIG. 20B.

The symbol interleaver 613 performs block interleaving in symbol unitson the data that are outputted from the byte-symbol converter 611.Subsequently, the symbol interleaver 613 outputs the interleaved data tothe symbol-byte converter 614. Herein, any type of interleaver that canrearrange the structural order may be used as the symbol interleaver 613of the present invention. In the example given in the present invention,a variable length interleaver that may be applied for symbols having awide range of lengths, the order of which is to be rearranged. Forexample, the symbol interleaver of FIG. 19 may also be used in the blockprocessor shown in FIG. 20A and FIG. 20B.

The symbol-byte converter 614 outputs the symbols having the rearrangingof the symbol order completed, in accordance with the rearranged order.Thereafter, the symbols are grouped to be configured in byte units,which are then outputted to the block formatter 620. More specifically,the symbol-byte converter 614 groups 4 symbols outputted from the symbolinterleaver 613 so as to configure a data byte. As shown in FIG. 21, theblock formatter 620 performs the process of aligning the output of eachsymbol-byte converter 612 and 614 within the block in accordance with aset standard. Herein, the block formatter 620 operates in associationwith the trellis encoding module 256.

More specifically, the block formatter 620 decides the output order ofthe mobile service data outputted from each symbol-byte converter 612and 614 while taking into consideration the place (or order) of the dataexcluding the mobile service data that are being inputted, wherein themobile service data include main service data, known data, RS paritydata, and MPEG header data.

According to the embodiment of the present invention, the trellisencoding module 256 is provided with 12 trellis encoders. FIG. 22illustrates a block diagram showing the trellis encoding module 256according to the present invention. In the example shown in FIG. 22, 12identical trellis encoders are combined to the interleaver in order todisperse noise. Herein, each trellis encoder may be provided with apre-coder.

FIG. 23A illustrates the block processor 303 being concatenated with thetrellis encoding module 256. In the transmitting system, a plurality ofblocks actually exists between the pre-processor 230 including the blockprocessor 303 and the trellis encoding module 256, as shown in FIG. 3.Conversely, the receiving system considers the pre-processor 230 to beconcatenated with the trellis encoding module 256, thereby performingthe decoding process accordingly. However, the data excluding the mobileservice data that are being inputted to the trellis encoding module 256,wherein the mobile service data include main service data, known data,RS parity data, and MPEG header data, correspond to data that are addedto the blocks existing between the block processor 303 and the trellisencoding module 256. FIG. 23B illustrates an example of a data processor650 being positioned between the block processor 303 and the trellisencoding module 256, while taking the above-described instance intoconsideration.

Herein, when the interleaving unit 610 of the block processor 303performs a ½-rate encoding process, the interleaving unit 610 may beconfigured as shown in FIG. 20A (or FIG. 20B). Referring to FIG. 3, forexample, the data processor 650 may include a group formatter 304, adata deinterleaver 305, a packet formatter 306, a packet multiplexer240, and a post-processor 250, wherein the post-processor 250 includes adata randomizer 251, a RS encoder/non-systematic RS encoder 252, a datainterleaver 253, a parity replacer 254, and a non-systematic RS encoder255.

At this point, the trellis encoding module 256 symbolizes the data thatare being inputted so as to divide the symbolized data and to send thedivided data to each trellis encoder in accordance with a pre-definedmethod. Herein, one byte is converted into 4 symbols, each beingconfigured of 2 bits. Also, the symbols created from the single databyte are all transmitted to the same trellis encoder. Accordingly, eachtrellis encoder pre-codes an upper bit of the input symbol, which isthen outputted as the uppermost output bit C2. Alternatively, eachtrellis encoder trellis-encodes a lower bit of the input symbol, whichis then outputted as two output bits C1 and C0. The block formatter 620is controlled so that the data byte outputted from each symbol-byteconverter can be transmitted to different trellis encoders.

Hereinafter, the operation of the block formatter 620 will now bedescribed in detail with reference to FIG. 16 to FIG. 27. Referring toFIG. 20A, for example, the data byte outputted from the symbol-byteconverter 612 and the data byte outputted from the symbol-byte converter614 are inputted to different trellis encoders of the trellis encodingmodule 256 in accordance with the control of the block formatter 620.Hereinafter, the data byte outputted from the symbol-byte converter 612will be referred to as X, and the data byte outputted from thesymbol-byte converter 614 will be referred to as Y, for simplicity.Referring to FIG. 21( a), each number (i.e., 0 to 11) indicates thefirst to twelfth trellis encoders of the trellis encoding module 256,respectively.

In addition, the output order of both symbol-byte converters arearranged (or aligned) so that the data bytes outputted from thesymbol-byte converter 612 are respectively inputted to the 0^(th) to5^(th) trellis encoders (0 to 5) of the trellis encoding module 256, andthat the data bytes outputted from the symbol-byte converter 614 arerespectively inputted to the 6^(th) to 11^(th) trellis encoders (6 to11) of the trellis encoding module 256. Herein, the trellis encodershaving the data bytes outputted from the symbol-byte converter 612allocated therein, and the trellis encoders having the data bytesoutputted from the symbol-byte converter 614 allocated therein aremerely examples given to simplify the understanding of the presentinvention. Furthermore, according to an embodiment of the presentinvention, and assuming that the input data of the block processor 303correspond to a block configured of 12 bytes, the symbol-byte converter612 outputs 12 data bytes from X0 to X11, and the symbol-byte converter614 outputs 12 data bytes from Y0 to Y11.

FIG. 21( b) illustrates an example of data being inputted to the trellisencoding module 256. Particularly, FIG. 21( b) illustrates an example ofnot only the mobile service data but also the main service data and RSparity data being inputted to the trellis encoding module 256, so as tobe distributed to each trellis encoder. More specifically, the mobileservice data outputted from the block processor 303 pass through thegroup formatter 304, from which the mobile service data are mixed withthe main service data and RS parity data and then outputted, as shown inFIG. 21( a). Accordingly, each data byte is respectively inputted to thetrellis encoders in accordance with the positions (or places) within thedata group after being data-interleaved.

Herein, when the output data bytes X and Y of the symbol-byte converters612 and 614 are allocated to each respective trellis encoder, the inputof each trellis encoder may be configured as shown in FIG. 21( b). Morespecifically, referring to FIG. 21( b), the six mobile service databytes (X0 to X5) outputted from the symbol-byte converter 612 aresequentially allocated (or distributed) to the first to sixth trellisencoders (0 to 5) of the trellis encoding module 256. Also, the 2 mobileservice data bytes Y0 and Y1 outputted from the symbol-byte converter614 are sequentially allocated to the 7^(th) and 8^(th) trellis encoders(6 and 7) of the trellis encoding module 256. Thereafter, among the 5main service data bytes, 4 data bytes are sequentially allocated to the9^(th) and 12^(th) trellis encoders (8 to 11) of the trellis encodingmodule 256. Finally, the remaining 1 byte of the main service data byteis allocated once again to the first trellis encoder (0).

It is assumed that the mobile service data, the main service data, andthe RS parity data are allocated to each trellis encoder, as shown inFIG. 21( b). It is also assumed that, as described above, the input ofthe block processor 303 is configured of 12 bytes, and that 12 bytesfrom X0 to X11 are outputted from the symbol-byte converter 612, andthat 12 bytes from Y0 to Y11 are outputted from the symbol-byteconverter 614. In this case, as shown in FIG. 21( c), the blockformatter 620 arranges the data bytes that are to be outputted from thesymbol-byte converters 612 and 614 by the order of X0 to X5, Y0, Y1, X6to X10, Y2 to Y7, X11, and Y8 to Y11. More specifically, the trellisencoder that is to perform the encoding process is decided based uponthe position (or place) within the transmission frame in which each databyte is inserted. At this point, not only the mobile service data butalso the main service data, the MPEG header data, and the RS parity dataare also inputted to the trellis encoding module 256. Herein, it isassumed that, in order to perform the above-described operation, theblock formatter 620 is informed of (or knows) the information on thedata group format after the data-interleaving process.

FIG. 24 illustrates a block diagram of the block processor performing anencoding process at a coding rate of 1/N according to an embodiment ofthe present invention. Herein, the block processor includes (N−1) numberof symbol interleavers 741 to 74N−1, which are configured in a parallelstructure. More specifically, the block processor having the coding rateof 1/N consists of a total of N number of branches (or paths) includinga branch (or path), which is directly transmitted to the block formatter730. In addition, the symbol interleaver 741 to 74N−1 of each branch mayeach be configured of a different symbol interleaver. Furthermore, (N−1)number of symbol-byte converter 751 to 75N−1 each corresponding to each(N−1) number of symbol interleavers 741 to 74N−1 may be included at theend of each symbol interleaver, respectively. Herein, the output data ofthe (N−1) number of symbol-byte converter 751 to 75N−1 are also inputtedto the block formatter 730.

In the example of the present invention, N is equal to or smaller than12. If N is equal to 12, the block formatter 730 may align the outputdata so that the output byte of the 12^(th) symbol-byte converter 75N−1is inputted to the 12^(th) trellis encoder. Alternatively, if N is equalto 3, the block formatter 730 may arranged the output order, so that thedata bytes outputted from the symbol-byte converter 720 are inputted tothe 1^(st) to 4^(th) trellis encoders of the trellis encoding module256, and that the data bytes outputted from the symbol-byte converter751 are inputted to the 5^(th) to 8^(th) trellis encoders, and that thedata bytes outputted from the symbol-byte converter 752 are inputted tothe 9^(th) to 12^(th) trellis encoders. At this point, the order of thedata bytes outputted from each symbol-byte converter may vary inaccordance with the position within the data group of the data otherthan the mobile service data, which are mixed with the mobile servicedata that are outputted from each symbol-byte converter.

FIG. 25 illustrates a detailed block diagram showing the structure of ablock processor according to another embodiment of the presentinvention. Herein, the block formatter is removed from the blockprocessor so that the operation of the block formatter may be performedby a group formatter. More specifically, the block processor of FIG. 25may include a byte-symbol converter 810, symbol-byte converters 820 and840, and a symbol interleaver 830. In this case, the output of eachsymbol-byte converter 820 and 840 is inputted to the group formatter850.

Also, the block processor may obtain a desired coding rate by addingsymbol interleavers and symbol-byte converters. If the system designerwishes a coding rate of 1/N, the block processor needs to be providedwith a total of N number of branches (or paths) including a branch (orpath), which is directly transmitted to the block formatter 850, and(N−1) number of symbol interleavers and symbol-byte convertersconfigured in a parallel structure with (N−1) number of branches. Atthis point, the group formatter 850 inserts place holders ensuring thepositions (or places) for the MPEG header, the non-systematic RS parity,and the main service data. And, at the same time, the group formatter850 positions the data bytes outputted from each branch of the blockprocessor.

The number of trellis encoders, the number of symbol-byte converters,and the number of symbol interleavers proposed in the present inventionare merely exemplary. And, therefore, the corresponding numbers do notlimit the spirit or scope of the present invention. It is apparent tothose skilled in the art that the type and position of each data bytebeing allocated to each trellis encoder of the trellis encoding module256 may vary in accordance with the data group format. Therefore, thepresent invention should not be understood merely by the examples givenin the description set forth herein. The mobile service data that areencoded at a coding rate of 1/N and outputted from the block processor303 are inputted to the group formatter 304. Herein, in the example ofthe present invention, the order of the output data outputted from theblock formatter of the block processor 303 are aligned and outputted inaccordance with the position of the data bytes within the data group.

Signaling Information Processing

The transmitter 200 according to the present invention may inserttransmission parameters by using a plurality of methods and in aplurality of positions (or places), which are then transmitted to thereceiving system. For simplicity, the definition of a transmissionparameter that is to be transmitted from the transmitter to thereceiving system will now be described. The transmission parameterincludes data group information, region information within a data group,the number of RS frames configuring a super frame (i.e., a super framesize (SFS)), the number of RS parity data bytes (P) for each columnwithin the RS frame, whether or not a checksum, which is added todetermine the presence of an error in a row direction within the RSframe, has been used, the type and size of the checksum if the checksumis used (presently, 2 bytes are added to the CRC), the number of datagroups configuring one RS frame—since the RS frame is transmitted to oneburst section, the number of data groups configuring the one RS frame isidentical to the number of data groups within one burst (i.e., burstsize (BS)), a turbo code mode, and a RS code mode.

Also, the transmission parameter required for receiving a burst includesa burst period—herein, one burst period corresponds to a value obtainedby counting the number of fields starting from the beginning of acurrent burst until the beginning of a next burst, a positioning orderof the RS frames that are currently being transmitted within a superframe (i.e., a permuted frame index (PFI)) or a positioning order ofgroups that are currently being transmitted within a RS frame (burst)(i.e., a group index (GI)), and a burst size. Depending upon the methodof managing a burst, the transmission parameter also includes the numberof fields remaining until the beginning of the next burst (i.e., time tonext burst (TNB)). And, by transmitting such information as thetransmission parameter, each data group being transmitted to thereceiving system may indicate a relative distance (or number of fields)between a current position and the beginning of a next burst.

The information included in the transmission parameter corresponds toexamples given to facilitate the understanding of the present invention.Therefore, the proposed examples do not limit the scope or spirit of thepresent invention and may be easily varied or modified by anyone skilledin the art. According to the first embodiment of the present invention,the transmission parameter may be inserted by allocating a predeterminedregion of the mobile service data packet or the data group. In thiscase, the receiving system performs synchronization and equalization ona received signal, which is then decoded by symbol units. Thereafter,the packet deformatter may separate the mobile service data and thetransmission parameter so as to detect the transmission parameter.According to the first embodiment, the transmission parameter may beinserted from the group formatter 304 and then transmitted.

According to the second embodiment of the present invention, thetransmission parameter may be multiplexed with another type of data. Forexample, when known data are multiplexed with the mobile service data, atransmission parameter may be inserted, instead of the known data, in aplace (or position) where a known data byte is to be inserted.Alternatively, the transmission parameter may be mixed with the knowndata and then inserted in the place where the known data byte is to beinserted. According to the second embodiment, the transmission parametermay be inserted from the group formatter 304 or from the packetformatter 306 and then transmitted.

According to a third embodiment of the present invention, thetransmission parameter may be inserted by allocating a portion of areserved region within a field synchronization segment of a transmissionframe. In this case, since the receiving system may perform decoding ona receiving signal by symbol units before detecting the transmissionparameter, the transmission parameter having information on theprocessing methods of the block processor 303 and the group formatter304 may be inserted in a reserved field of a field synchronizationsignal. More specifically, the receiving system obtains fieldsynchronization by using a field synchronization segment so as to detectthe transmission parameter from a pre-decided position. According to thethird embodiment, the transmission parameter may be inserted from thesynchronization multiplexer 240 and then transmitted.

According to the fourth embodiment of the present invention, thetransmission parameter may be inserted in a layer (or hierarchicalregion) higher than a transport stream (TS) packet. In this case, thereceiving system should be able to receive a signal and process thereceived signal to a layer higher than the TS packet in advance. At thispoint, the transmission parameter may be used to certify thetransmission parameter of a currently received signal and to provide thetransmission parameter of a signal that is to be received in a laterprocess.

In the present invention, the variety of transmission parametersassociated with the transmission signal may be inserted and transmittedby using the above-described methods according to the first to fourthembodiment of the present invention. At this point, the transmissionparameter may be inserted and transmitted by using only one of the fourembodiments described above, or by using a selection of theabove-described embodiments, or by using all of the above-describedembodiments. Furthermore, the information included in the transmissionparameter may be duplicated and inserted in each embodiment.Alternatively, only the required information may be inserted in thecorresponding position of the corresponding embodiment and thentransmitted. Furthermore, in order to ensure robustness of thetransmission parameter, a block encoding process of a short cycle (orperiod) may be performed on the transmission parameter and, then,inserted in a corresponding region. The method for performing ashort-period block encoding process on the transmission parameter mayinclude, for example, Kerdock encoding, BCH encoding, RS encoding, andrepetition encoding of the transmission parameter. Also, a combinationof a plurality of block encoding methods may also be performed on thetransmission parameter.

The transmission parameters may be grouped to create a block code of asmall size, so as to be inserted in a byte place allocated within thedata group for signaling and then transmitted. However, in this case,the block code passes through the block decoded from the receiving endso as to obtain a transmission parameter value. Therefore, thetransmission parameters of the turbo code mode and the RS code mode,which are required for block decoding, should first be obtained.Accordingly, the transmission parameters associated with a particularmode may be inserted in a specific section of a known data region. And,in this case, a correlation of with a symbol may be used for a fasterdecoding process. The receiving system refers to the correlation betweeneach sequence and the currently received sequences, thereby determiningthe encoding mode and the combination mode.

Meanwhile, when the transmission parameter is inserted in the fieldsynchronization segment region or the known data region and thentransmitted, and when the transmission parameter has passed through thetransmission channel, the reliability of the transmission parameter isdeteriorated. Therefore, one of a plurality of pre-defined patterns mayalso be inserted in accordance with the corresponding transmissionparameter. Herein, the receiving system performs a correlationcalculation between the received signal and the pre-defined patterns soas to recognize the transmission parameter. For example, it is assumedthat a burst including 5 data groups is pre-decided as pattern A basedupon an agreement between the transmitting system and the receivingsystem. In this case, the transmitting system inserts and transmitspattern A, when the number of groups within the burst is equal to 5.Thereafter, the receiving system calculates a correlation between thereceived data and a plurality of reference patterns including pattern A,which was created in advance. At this point, if the correlation valuebetween the received data and pattern A is the greatest, the receiveddata indicates the corresponding parameter, and most particularly, thenumber of groups within the burst. At this point, the number of groupsmay be acknowledged as 5. Hereinafter, the process of inserting andtransmitting the transmission parameter will now be described accordingto first, second, and third embodiments of the present invention.

First Embodiment

FIG. 26 illustrates a schematic diagram of the group formatter 304receiving the transmission parameter and inserting the receivedtransmission parameter in region A of the data group according to thepresent invention. Herein, the group formatter 304 receives mobileservice data from the block processor 303. Conversely, the transmissionparameter is processed with at least one of a data randomizing process,a RS frame encoding process, and a block processing process, and maythen be inputted to the group formatter 304. Alternatively, thetransmission parameter may be directly inputted to the group formatter304 without being processed with any of the above-mentioned processes.In addition, the transmission parameter may be provided from the servicemultiplexer 100. Alternatively, the transmission parameter may also begenerated and provided from within the transmitter 200. The transmissionparameter may also include information required by the receiving systemin order to receive and process the data included in the data group. Forexample, the transmission parameter may include data group information,and multiplexing information.

The group formatter 304 inserts the mobile service data and transmissionparameter which are to be inputted to corresponding regions within thedata group in accordance with a rule for configuring a data group. Forexample, the transmission parameter passes through a block encodingprocess of a short period and is, then, inserted in region A of the datagroup. Particularly, the transmission parameter may be inserted in apre-arranged and arbitrary position (or place) within region A. If it isassumed that the transmission parameter has been block encoded by theblock processor 303, the block processor 303 performs the same dataprocessing operation as the mobile service data, more specifically,either a ½-rate encoding or ¼-rate encoding process on the signalinginformation including the transmission parameter. Thereafter, the blockprocessor 303 outputs the processed transmission parameter to the groupformatter 304. Thereafter, the signaling information is also recognizedas the mobile service data and processed accordingly.

FIG. 27 illustrates a block diagram showing an example of the blockprocessor receiving the transmission parameter and processing thereceived transmission parameter with the same process as the mobileservice data. Particularly, FIG. 27 illustrates an example showing thestructure of FIG. 16 further including a signaling information provider411 and multiplexer 412. More specifically, the signaling informationprovider 411 outputs the signaling information including thetransmission parameter to the multiplexer 412. The multiplexer 412multiplexes the signaling information and the output of the RS frameencoder 302. Then, the multiplexer 412 outputs the multiplexed data tothe byte-bit converter 401.

The byte-bit converter 401 divides the mobile service data bytes orsignaling information byte outputted from the multiplexer 412 into bits,which are then outputted to the symbol encoder 402. The subsequentoperations are identical to those described in FIG. 16. Therefore, adetailed description of the same will be omitted for simplicity. If anyof the detailed structures of the block processor 303 shown in FIG. 20,FIG. 23, FIG. 24, and FIG. 25, the signaling information provider 411and the multiplexer 412 may be provided behind the byte-symbolconverter.

Second Embodiment

Meanwhile, when known data generated from the group formatter inaccordance with a pre-decided rule are inserted in a correspondingregion within the data group, a transmission parameter may be insertedin at least a portion of a region, where known data may be inserted,instead of the known data. For example, when a long known data sequenceis inserted at the beginning of region A within the data group, atransmission parameter may be inserted in at least a portion of thebeginning of region A instead of the known data. A portion of the knowndata sequence that is inserted in the remaining portion of region A,excluding the portion in which the transmission parameter is inserted,may be used to detect a starting point of the data group by thereceiving system. Alternatively, another portion of region A may be usedfor channel equalization by the receiving system.

In addition, when the transmission parameter is inserted in the knowndata region instead of the actual known data. The transmission parametermay be block encoded in short periods and then inserted. Also, asdescribed above, the transmission parameter may also be inserted basedupon a pre-defined pattern in accordance with the transmissionparameter. If the group formatter 304 inserts known data place holdersin a region within the data group, wherein known data may be inserted,instead of the actual known data, the transmission parameter may beinserted by the packet formatter 306. More specifically, when the groupformatter 304 inserts the known data place holders, the packet formatter306 may insert the known data instead of the known data place holders.Alternatively, when the group formatter 304 inserts the known data, theknown data may be directly outputted without modification. FIG. 28illustrates a block diagram showing the structure of a packet formatter306 being expanded so that the packet formatter 306 can insert thetransmission parameter according to an embodiment of the presentinvention. More specifically, the structure of the packet formatter 306further includes a known data generator 351 and a signaling multiplexer352. For example, the transmission parameter being inputted to thesignaling multiplexer 352 may include mode information designating thecoding rate of each region within the data group.

For example, when the SCCC mode value that is extracted from the knowndata region is equal to ‘3’, this indicates that region A and region Cwithin the corresponding data group are encoded at a coding rate of ½and that region B is encoded at a coding rate of ¼. The transmittingsystem of the present invention generates 6 patterns corresponding toeach mode value shown in Table 1 based upon an agreement between thetransmitting system and the receiving system. Herein, the correspondingpattern may be inserted in the known data region for each data group. Inthis case, the receiving system may obtain the SCCC mode informationfrom the known data region prior to performing a decoding process inaccordance with the corresponding SCCC mode.

The signaling multiplexer 352 selects one of the transmission parameterand the known data generated from the known data generator 351 and,then, outputs the selected data to the packet formatter 306. The packetformatter 306 inserts the known data or transmission parameter outputtedfrom the signaling multiplexer 352 into the known data place holdersoutputted from the data interleaver 305. Then, the packet formatter 306outputs the processed data. More specifically, the packet formatter 306inserts a transmission parameter in at least a portion of the known dataregion instead of the known data, which is then outputted. For example,when a known data place holder is inserted at a beginning portion ofregion A within the data group, a transmission parameter may be insertedin a portion of the known data place holder instead of the actual knowndata.

Also, when the transmission parameter is inserted in the known dataplace holder instead of the known data, the transmission parameter maybe block encoded in short periods and inserted. Alternatively, apre-defined pattern may be inserted in accordance with the transmissionparameter. More specifically, the signaling multiplexer 352 multiplexesthe known data and the transmission parameter (or the pattern defined bythe transmission parameter) so as to configure a new known datasequence. Then, the signaling multiplexer 352 outputs the newlyconfigured known data sequence to the packet formatter 306. The packetformatter 306 deletes the main service data place holder and RS parityplace holder from the output of the data interleaver 305, and creates amobile service data packet of 188 bytes by using the mobile servicedata, MPEG header, and the output of the signaling multiplexer. Then,the packet formatter 306 outputs the newly created mobile service datapacket to the packet multiplexer 240.

In this case, the region A of each data group has a different known datapattern. Therefore, the receiving system separates only the symbol in apre-arranged section of the known data sequence and recognizes theseparated symbol as the transmission parameter. Herein, depending uponthe design of the transmitting system, the known data may be inserted indifferent blocks, such as the packet formatter 306, the group formatter304, or the block processor 303. Therefore, a transmission parameter maybe inserted instead of the known data in the block wherein the knowndata are to be inserted.

According to the second embodiment of the present invention, atransmission parameter including information on the processing method ofthe block processor 303 may be inserted in a portion of the known dataregion and then transmitted. In this case, a symbol processing methodand position of the symbol for the actual transmission parameter symbolare already decided. Also, the position of the transmission parametersymbol should be positioned so as to be transmitted or received earlierthan any other data symbols that are to be decoded. Accordingly, thereceiving system may detect the transmission symbol before the datasymbol decoding process, so as to use the detected transmission symbolfor the decoding process.

Third Embodiment

Meanwhile, the transmission parameter may also be inserted in the fieldsynchronization segment region and then transmitted. FIG. 29 illustratesa block diagram showing the synchronization multiplexer being expandedin order to allow the transmission parameter to be inserted in the fieldsynchronization segment region. Herein, a signaling multiplexer 261 isfurther included in the synchronization multiplexer 260. Thetransmission parameter of the general VSB method is configured of 2fields. More specifically, each field is configured of one fieldsynchronization segment and 312 data segments. Herein, the first 4symbols of a data segment correspond to the segment synchronizationportion, and the first data segment of each field corresponds to thefield synchronization portion.

One field synchronization signal is configured to have the length of onedata segment. The data segment synchronization pattern exists in thefirst 4 symbols, which are then followed by pseudo random sequences PN511, PN 63, PN 63, and PN 63. The next 24 symbols include informationassociated with the VSB mode. Additionally, the 24 symbols that includeinformation associated with the VSB mode are followed by the remaining104 symbols, which are reserved symbols. Herein, the last 12 symbols ofa previous segment are copied and positioned as the last 12 symbols inthe reserved region. In other words, only the 92 symbols in the fieldsynchronization segment are the symbols that correspond to the actualreserved region.

Therefore, the signaling multiplexer 261 multiplexes the transmissionparameter with an already-existing field synchronization segment symbol,so that the transmission parameter can be inserted in the reservedregion of the field synchronization segment. Then, the signalingmultiplexer 261 outputs the multiplexed transmission parameter to thesynchronization multiplexer 260. The synchronization multiplexer 260multiplexes the segment synchronization symbol, the data symbols, andthe new field synchronization segment outputted from the signalingmultiplexer 261, thereby configuring a new transmission frame. Thetransmission frame including the field synchronization segment, whereinthe transmission parameter is inserted, is outputted to the transmissionunit 270. At this point, the reserved region within the fieldsynchronization segment for inserting the transmission parameter maycorrespond to a portion of or the entire 92 symbols of the reservedregion. Herein, the transmission parameter being inserted in thereserved region may, for example, include information identifying thetransmission parameter as the main service data, the mobile servicedata, or a different type of mobile service data.

If the information on the processing method of the block processor 303is transmitted as a portion of the transmission parameter, and when thereceiving system wishes to perform a decoding process corresponding tothe block processor 303, the receiving system should be informed of suchinformation on the block processing method in order to perform thedecoding process. Therefore, the information on the processing method ofthe block processor 303 should already be known prior to the blockdecoding process. Accordingly, as described in the third embodiment ofthe present invention, when the transmission parameter having theinformation on the processing method of the block processor 303 (and/orthe group formatter 304) is inserted in the reserved region of the fieldsynchronization signal and then transmitted, the receiving system iscapable of detecting the transmission parameter prior to performing theblock decoding process on the received signal.

Receiving System

FIG. 30 illustrates a block diagram showing a structure of a digitalbroadcast receiving system according to the present invention. Thedigital broadcast receiving system of FIG. 30 uses known datainformation, which is inserted in the mobile service data section and,then, transmitted by the transmitting system, so as to perform carriersynchronization recovery, frame synchronization recovery, and channelequalization, thereby enhancing the receiving performance. Referring toFIG. 30, the digital broadcast receiving system includes a tuner 1001, ademodulator 1002, an equalizer 1003, a known data detector 1004, a blockdecoder 1005, a data deformatter 1006, a RS frame decoder 1007, aderandomizer 1008, a data deinterleaver 1009, a RS decoder 1010, and adata derandomizer 1011. Herein, for simplicity of the description of thepresent invention, the data deformatter 1006, the RS frame decoder 1007,and the derandomizer 1008 will be collectively referred to as a mobileservice data processing unit. And, the data deinterleaver 1009, the RSdecoder 1010, and the data derandomizer 1011 will be collectivelyreferred to as a main service data processing unit.

More specifically, the tuner 1001 tunes a frequency of a particularchannel and down-converts the tuned frequency to an intermediatefrequency (IF) signal. Then, the tuner 1001 outputs the down-convertedIF signal to the demodulator 1002 and the known data detector 1004. Thedemodulator 1002 performs self gain control, carrier recovery, andtiming recovery processes on the inputted IF signal, thereby modifyingthe IF signal to a baseband signal. Herein, an analog/digital converter(ADC) converting pass band analog IF signals to digital IF signals maybe included between the tuner 1001 and the demodulator 1002. Then, thedemodulator 1002 outputs the digitalized and inputted pass band IFsignal to the equalizer 1003 and the known data detector 1004. Theequalizer 1003 compensates the distortion of the channel included in thedemodulated signal and then outputs the error-compensated signal to theblock decoder 1005.

At this point, the known data detector 1004 detects the known sequenceplace inserted by the transmitting end from the input/output data of thedemodulator 1002 (i.e., the data prior to the demodulation process orthe data after the demodulation process). Thereafter, the placeinformation (or position indicator) along with the symbol sequence ofthe known data, which are generated from the detected place, isoutputted to the demodulator 1002 and the equalizer 1003. Also, theknown data detector 1004 outputs a set of information to the blockdecoder 1005. This set of information is used to allow the block decoder1005 of the receiving system to identify the mobile service data thatare processed with additional encoding from the transmitting system andthe main service data that are not processed with additional encoding.In addition, although the connection status is not shown in FIG. 30, theinformation detected from the known data detector 1004 may be usedthroughout the entire receiving system and may also be used in the datadeformatter 1006 and the RS frame decoder 1007.

The demodulator 1002 uses the known data (or sequence) positionindicator and the known data symbol sequence during the timing and/orcarrier recovery, thereby enhancing the demodulating performance.Similarly, the equalizer 1003 uses the known sequence position indicatorand the known data symbol sequence so as to enhance the equalizingperformance. Moreover, the decoding result of the block decoder 1005 maybe fed-back to the equalizer 1003, thereby enhancing the equalizingperformance.

Demodulator and Known Sequence Detector within Receiving System

At this point, the transmitting system may periodically insert andtransmit known data within a transmission frame, as shown in FIG. 7A andFIG. 8.

FIG. 31 illustrates an example of known data sequence being periodicallyinserted and transmitted in-between actual data by the transmittingsystem. Referring to FIG. 31, AS represents the number of valid datasymbols, and BS represents the number of known data symbols. Therefore,BS number of known data symbols are inserted and transmitted at a periodof (AS+BS) symbols. Herein, AS may correspond to mobile service data,main service data, or a combination of mobile service data and mainservice data. In order to be differentiated from the known data, datacorresponding to AS will hereinafter be referred to as valid data.

Referring to FIG. 31, known data sequence having the same pattern areincluded in each known data section that is being periodically inserted.Herein, the length of the known data sequence having identical datapatterns may be either equal to or different from the length of theentire (or total) known data sequence of the corresponding known datasection (or block). If the two lengths are different from one another,the length of the entire known data sequence should be longer than thelength of the known data sequence having identical data patterns. Inthis case, the same known data sequences are included in the entireknown data sequence. The known data detector 1004 detects the positionof the known data being periodically inserted and transmitted asdescribed above. At the same time, the known data detector 1004 may alsoestimate initial frequency offset during the process of detecting knowndata. In this case, the demodulator 1002 may estimate with more accuracycarrier frequency offset from the information on the known data position(or known sequence position indicator) and initial frequency offsetestimation value, thereby compensating the estimated initial frequencyoffset.

FIG. 32 is a flow chart illustrating a method of detecting positions ofknown data according to one aspect of the present invention. The knownsequence detector 1004 initially detects the position of the first knowndata region using a plurality of repeated data patterns included in thefifth sub-region of the first known data region (2001). Next, the knownsequence detector 1004 can estimate the position of the field syncsegment from the detected position of the first known data regionaccording to protocol (2002), and can further estimate positions of thesecond, third, fourth, and fifth known data regions in a similar manner(2003). The estimated position information of the filed sync and knowndata regions are provided to the demodulator 1002 and the channelequalizer 1003. For example, the position information of the field syncand CIR TS region of each known data region is provided to the equalizer1003. Then the equalizer 1003 estimates a channel impulse response (CIR)using these position information.

FIG. 33 illustrates a detailed block diagram of a demodulator accordingto the present invention. Referring to FIG. 33, the demodulator includesa phase splitter 1010, a numerically controlled oscillator (NCO) 1020, afirst multiplier 1030, a resampler 1040, a second multiplier 1050, amatched filter 1060, a DC remover 1070, a timing recovery unit 1080, acarrier recovery unit 1090, and a phase compensator 1110. Herein, theknown sequence detector 1004 includes a known sequence detector andinitial frequency offset estimator 1004-1 for estimating known datainformation and initial frequency offset. Also referring to FIG. 33, thephase splitter 1010 receives a pass band digital signal and splits thereceived signal into a pass band digital signal of a real number elementand a pass band digital signal of an imaginary number element bothhaving a phase of 90 degrees between one another. In other words, thepass band digital signal is split into complex signals. The splitportions of the pass band digital signal are then outputted to the firstmultiplier 1030. Herein, the real number signal outputted from the phasesplitter 1010 will be referred to as an ‘I’ signal, and the imaginarynumber signal outputted from the phase splitter 1010 will be referred toas a ‘Q’ signal, for simplicity of the description of the presentinvention.

The first multiplier 1030 multiplies the I and Q pass band digitalsignals, which are outputted from the phase splitter 1010, to a complexsignal having a frequency proportional to a constant being outputtedfrom the NCO 1020, thereby changing the I and Q pass band digitalsignals to baseband digital complex signals. Then, the baseband digitalsignals of the first multiplier 1030 are inputted to the resampler 1040.The resampler 1040 resamples the signals being outputted from the firstmultiplier 1030 so that the signal corresponds to the timing clockprovided by the timing recovery unit 1080. Thereafter, the resampler1040 outputs the resampled signals to the second multiplier 1050.

For example, when the analog/digital converter uses a 25 MHz fixedoscillator, the baseband digital signal having a frequency of 25 MHz,which is created by passing through the analog/digital converter, thephase splitter 1010, and the first multiplier 1030, is processed with aninterpolation process by the resampler 1040. Thus, the interpolatedsignal is recovered to a baseband digital signal having a frequencytwice that of the receiving signal of a symbol clock (i.e., a frequencyof 21.524476 MHz). Alternatively, if the analog/digital converter usesthe timing clock of the timing recovery unit 1080 as the samplingfrequency (i.e., if the analog/digital converter uses a variablefrequency) in order to perform an A/D conversion process, the resampler1040 is not required and may be omitted.

The second multiplier 1050 multiplies an output frequency of the carrierrecovery unit 1090 with the output of the resampler 1040 so as tocompensate any remaining carrier included in the output signal of theresampler 1040. Thereafter, the compensated carrier is outputted to thematched filter 1060 and the timing recovery unit 1080. The signalmatched-filtered by the matched filter 1060 is inputted to the DCremover 1070, the known sequence detector and initial frequency offsetestimator 1004-1, and the carrier recovery unit 1090.

The known sequence detector and initial frequency offset estimator1004-1 detects the place (or position) of the known data sequences thatare being periodically or non-periodically transmitted. Simultaneously,the known sequence detector and initial frequency offset estimator1004-1 estimates an initial frequency offset during the known sequencedetection process. More specifically, while the transmission data frameis being received, as shown in FIG. 5, the known sequence detector andinitial frequency offset estimator 1004-1 detects the position (orplace) of the known data included in the transmission data frame. Then,the known sequence detector and initial frequency offset estimator1004-1 outputs the detected information on the known data place (i.e., aknown sequence position indicator) to the timing recovery unit 1080, thecarrier recovery unit 1090, and the phase compensator 1110 of thedemodulator 1002 and the equalizer 1003. Furthermore, the known sequencedetector and initial frequency offset estimator 1004-1 estimates theinitial frequency offset, which is then outputted to the carrierrecovery unit 1090. At this point, the known sequence detector andinitial frequency offset estimator 1004-1 may either receive the outputof the matched filter 1060 or receive the output of the resampler 1040.This may be optionally decided depending upon the design of the systemdesigner.

The timing recovery unit 1080 uses the output of the second multiplier1050 and the known sequence position indicator detected from the knownsequence detector and initial frequency offset estimator 1004-1, so asto detect the timing error and, then, to output a sampling clock beingin proportion with the detected timing error to the resampler 1040,thereby adjusting the sampling timing of the resampler 1040. At thispoint, the timing recovery unit 1080 may receive the output of thematched filter 1060 instead of the output of the second multiplier 1050.This may also be optionally decided depending upon the design of thesystem designer.

Meanwhile, the DC remover 1070 removes a pilot tone signal (i.e., DCsignal), which has been inserted by the transmitting system, from thematched-filtered signal. Thereafter, the DC remover 1070 outputs theprocessed signal to the phase compensator 1110. The phase compensator1110 uses the data having the DC removed by the DC remover 1070 and theknown sequence position indicator detected by the known sequencedetector and initial frequency offset estimator 1004-1 to estimate thefrequency offset and, then, to compensate the phase change included inthe output of the DC remover 1070. The data having its phase changecompensated are inputted to the equalizer 1003. Herein, the phasecompensator 1110 is optional. If the phase compensator 1110 is notprovided, then the output of the DC remover 1070 is inputted to theequalizer 1003 instead.

FIG. 34 includes detailed block diagrams of the timing recovery unit1080, the carrier recovery unit 1090, and the phase compensator 1110 ofthe demodulator. According to an embodiment of the present invention,the carrier recovery unit 1090 includes a buffer 1091, a frequencyoffset estimator 1092, a loop filter 1093, a holder 1094, an adder 1095,and a NCO 1096. Herein, a decimator may be included before the buffer1091. The timing recovery unit 1080 includes a decimator 1081, a buffer1082, a timing error detector 1083, a loop filter 1084, a holder 1085,and a NCO 1086. Finally, the phase compensator 1110 includes a buffer1111, a frequency offset estimator 1112, a holder 1113, a NCO 1114, anda multiplier 1115. Furthermore, a decimator 1200 may be included betweenthe phase compensator 1110 and the equalizer 1003. The decimator 1200may be outputted in front of the DC remover 1070 instead of at theoutputting end of the phase compensator 1110.

Herein, the decimators correspond to components required when a signalbeing inputted to the demodulator is oversampled to N times by theanalog/digital converter. More specifically, the integer N representsthe sampling rate of the received signal. For example, when the inputsignal is oversampled to 2 times (i.e., when N=2) by the analog/digitalconverter, this indicates that two samples are included in one symbol.In this case, each of the decimators corresponds to a ½ decimator.Depending upon whether or not the oversampling process of the receivedsignal has been performed, the signal may bypass the decimators.

Meanwhile, the output of the second multiplier 1050 is temporarilystored in the decimator 1081 and the buffer 1082 both included in thetiming recovery unit 1080. Subsequently, the temporarily stored outputdata are inputted to the timing error detector 1083 through thedecimator 1081 and the buffer 1082. Assuming that the output of thesecond multiplier 1050 is oversampled to N times its initial state, thedecimator 1081 decimates the output of the second multiplier 1050 at adecimation rate of 1/N. Then, the 1/N-decimated data are inputted to thebuffer 1082. In other words, the decimator 1081 performs decimation onthe input signal in accordance with a VSB symbol cycle. Furthermore, thedecimator 1081 may also receive the output of the matched filter 1060instead of the output of the second multiplier 1050. The timing errordetector 1083 uses the data prior to or after being processed withmatched-filtering and the known sequence position indicator outputtedfrom the known sequence detector and initial frequency offset estimator1004-1 in order to detect a timing error. Thereafter, the detectedtiming error is outputted to the loop filter 1084. Accordingly, thedetected timing error information is obtained once during eachrepetition cycle of the known data sequence.

For example, if a known data sequence having the same pattern isperiodically inserted and transmitted, as shown in FIG. 37, the timingerror detector 1083 may use the known data in order to detect the timingerror. There exists a plurality of methods for detecting timing error byusing the known data. In the example of the present invention, thetiming error may be detected by using a correlation characteristicbetween the known data and the received data in the time domain, theknown data being already known in accordance with a pre-arrangedagreement between the transmitting system and the receiving system. Thetiming error may also be detected by using the correlationcharacteristic of the two known data types being received in thefrequency domain. Thus, the detected timing error is outputted. Inanother example, a spectral lining method may be applied in order todetect the timing error. Herein, the spectral lining method correspondsto a method of detecting timing error by using sidebands of the spectrumincluded in the received signal.

The loop filter 1084 filters the timing error detected by the timingerror detector 1083 and, then, outputs the filtered timing error to theholder 1085. The holder 1085 holds (or maintains) the timing errorfiltered and outputted from the loop filter 1084 during a pre-determinedknown data sequence cycle period and outputs the processed timing errorto the NCO 1086. Herein, the order of positioning of the loop filter1084 and the holder 1085 may be switched with one another. Inadditionally, the function of the holder 1085 may be included in theloop filter 1084, and, accordingly, the holder 1085 may be omitted. TheNCO 1086 accumulates the timing error outputted from the holder 1085.Thereafter, the NCO 1086 outputs the phase element (i.e., a samplingclock) of the accumulated timing error to the resampler 1040, therebyadjusting the sampling timing of the resampler 1040.

Meanwhile, the buffer 1091 of the carrier recovery unit 1090 may receiveeither the data inputted to the matched filter 1060 or the dataoutputted from the matched filter 1060 and, then, temporarily store thereceived data. Thereafter, the temporarily stored data are outputted tothe frequency offset estimator 1092. If a decimator is provided in frontof the buffer 1091, the input data or output data of the matched filter1060 are decimated by the decimator at a decimation rate of 1/N.Thereafter, the decimated data are outputted to the buffer 1091. Forexample, when the input data or output data of the matched filter 1060are oversampled to 2 times (i.e., when N=2), this indicates that theinput data or output data of the matched filter 1060 are decimated at arate of ½ by the decimator 1081 and then outputted to the buffer 1091.More specifically, when a decimator is provided in front of the buffer1091, the carrier recovery unit 1090 operates in symbol units.Alternatively, if a decimator is not provided, the carrier recovery unit1090 operates in oversampling units.

The frequency offset estimator 1092 uses the input data or output dataof the matched filter 1060 and the known sequence position indicatoroutputted from the known sequence detector and initial frequency offsetestimator 1004-1 in order to estimate the frequency offset. Then, theestimated frequency offset is outputted to the loop filter 1093.Therefore, the estimated frequency offset value is obtained once everyrepetition period of the known data sequence. The loop filter 1093performs low pass filtering on the frequency offset value estimated bythe frequency offset estimator 1092 and outputs the low pass-filteredfrequency offset value to the holder 1094. The holder 1094 holds (ormaintains) the low pass-filtered frequency offset value during apre-determined known data sequence cycle period and outputs thefrequency offset value to the adder 1095. Herein, the positions of theloop filter 1093 and the holder 1094 may be switched from one to theother. Furthermore, the function of the holder 1085 may be included inthe loop filter 1093, and, accordingly, the holder 1094 may be omitted.

The adder 1095 adds the value of the initial frequency offset estimatedby the known sequence detector and initial frequency offset estimator1004-1 to the frequency offset value outputted from the loop filter 1093(or the holder 1094). Thereafter, the added offset value is outputted tothe NCO 1096. Herein, if the adder 1095 is designed to also receive theconstant being inputted to the NCO 1020, the NCO 1020 and the firstmultiplier 1030 may be omitted. In this case, the second multiplier 1050may simultaneously perform changing signals to baseband signals andremoving remaining carrier.

The NCO 1096 generates a complex signal corresponding to the frequencyoffset outputted from the adder 1095, which is then outputted to thesecond multiplier 1050. Herein, the NCO 1096 may include a ROM. In thiscase, the NCO 1096 generates a compensation frequency corresponding tothe frequency offset being outputted from the adder 1095. Then, the NCO1096 reads a complex cosine corresponding to the compensation frequencyfrom the ROM, which is then outputted to the second multiplier 1050. Thesecond multiplier 1050 multiplies the output of the NCO 1094 included inthe carrier recovery unit 1090 to the output of the resampler 1040, soas to remove the carrier offset included in the output signal of theresampler 1040.

FIG. 35 illustrates a detailed block diagram of the frequency offsetestimator 1092 of the carrier recovery unit 1090 according to anembodiment of the present invention. Herein, the frequency offsetestimator 1092 operates in accordance with the known sequence positionindicator detected from the known sequence detector and initialfrequency offset estimator 1004-1. At this point, if the input data oroutput data of the matched filter 1060 are inputted through thedecimator, the frequency offset estimator 1092 operates in symbol units.Alternatively, if a decimator is not provided, the frequency offsetestimator 1092 operates in oversampling units. In the example given inthe description of the present invention, the frequency offset estimator1092 operates in symbol units. Referring to FIG. 35, the frequencyoffset estimator 1092 includes a controller 1310, a first N symbolbuffer 1301, a K symbol delay 1302, a second N symbol buffer 1303, aconjugator 1304, a multiplier 1305, an accumulator 1306, a phasedetector 1307, a multiplier 1308, and a multiplexer 1309. The frequencyoffset estimator 1092 having the above-described structure, as shown inFIG. 35, will now be described in detail with respect to an operationexample during a known data section.

The first N symbol buffer 1301 may store a maximum of N number of symbolbeing inputted thereto. The symbol data that are temporarily stored inthe first N symbol buffer 1301 are then inputted to the multiplier 1305.At the same time, the inputted symbol is inputted to the K symbol delay1302 so as to be delayed by K symbols. Thereafter, the delayed symbolpasses through the second N symbol buffer 1303 so as to be conjugated bythe conjugator 1304. Thereafter, the conjugated symbol is inputted tothe multiplier 1305. The multiplier 1305 multiplies the output of thefirst N symbol buffer 1301 and the output of the conjugator 1304. Then,the multiplier 1305 outputs the multiplied result to the accumulator1306. Subsequently, the accumulator 1306 accumulates the output of themultiplier 1305 during N symbol periods, thereby outputted theaccumulated result to the phase detector 1307.

The phase detector 1307 extracts the corresponding phase informationfrom the output of the accumulator 1306, which is then outputted to themultiplier 1308. The multiplier 1308 then divides the phase informationby K, thereby outputting the divided result to the multiplexer 1309.Herein, the result of the phase information divided by becomes thefrequency offset estimation value. More specifically, at the point wherethe input of the known data ends or at a desired point, the frequencyoffset estimator 1092 accumulates during an N symbol periodmultiplication of the complex conjugate of N number of the input datastored in the first N symbol buffer 1301 and the complex conjugate ofthe N number of the input data that are delayed by K symbols and storedin the second N symbol buffer 1303. Thereafter, the accumulated value isdivided by K, thereby extracting the frequency offset estimation value.

Based upon a control signal of the controller 1310, the multiplexer 1309selects either the output of the multiplier 1308 or ‘0’ and, then,outputs the selected result as the final frequency offset estimationvalue. The controller 1310 receives the known data sequence positionindicator from the known sequence detector and initial frequency offsetestimator 1004-1 in order to control the output of the multiplexer 1309.More specifically, the controller 1310 determines based upon the knowndata sequence position indicator whether the frequency offset estimationvalue being outputted from the multiplier 1308 is valid. If thecontroller 1310 determines that the frequency offset estimation value isvalid, the multiplexer 1309 selects the output of the multiplier 1308.Alternatively, if the controller 1310 determines that the frequencyoffset estimation value is invalid, the controller 1310 generates acontrol signal so that the multiplexer 1309 selects ‘0’. At this point,it is preferable that the input signals stored in the first N symbolbuffer 1301 and in the second N symbol buffer 1303 correspond to signalseach being transmitted by the same known data and passing through almostthe same channel. Otherwise, due to the influence of the transmissionchannel, the frequency offset estimating performance may be largelydeteriorated.

Further, the values N and K of the frequency offset estimator 1092(shown in FIG. 35) may be diversely decided. This is because aparticular portion of the known data that are identically repeated maybe used herein. For example, when the data having the structuredescribed in FIG. 37 are being transmitted, N may be set as BS (i.e.,N=BS), and K may be set as (AS+BS) (i.e., K=AS+BS)). The frequencyoffset estimation value range of the frequency offset estimator 1092 isdecided in accordance with the value K. If the value K is large, thenthe frequency offset estimation value range becomes smaller.Alternatively, if the value K is small, then the frequency offsetestimation value range becomes larger. Therefore, when the data havingthe structure of FIG. 37 is transmitted, and if the repetition cycle(AS+BS) of the known data is long, then the frequency offset estimationvalue range becomes smaller.

In this case, even if the initial frequency offset is estimated by theknown sequence detector and initial frequency offset estimator 1004-1,and if the estimated value is compensated by the second multiplier 1050,the remaining frequency offset after being compensated will exceed theestimation range of the frequency offset estimator 1092. In order toovercome such problems, the known data sequence that is regularlytransmitted may be configured of a repetition of a same data portion byusing a cyclic extension process. For example, if the known datasequence shown in FIG. 37 is configured of two identical portions havingthe length of BS/2, then the N and K values of the frequency offsetestimator 1092 (shown in FIG. 35) may be respectively set as B/2 and B/2(i.e., N=BS/2 and K=BS/2). In this case, the estimation value range maybecome larger than when using repeated known data.

Meanwhile, the known sequence detector and initial frequency offsetestimator 1004-1 detects the place (o position) of the known datasequences that are being periodically or non-periodically transmitted.Simultaneously, the known sequence detector and initial frequency offsetestimator 1004-1 estimates an initial frequency offset during the knownsequence detection process. The known data sequence position indicatordetected by the known sequence detector and initial frequency offsetestimator 1004-1 is outputted to the timing recovery unit 1080, thecarrier recovery unit 1090, and the phase compensator 1110 of thedemodulator 1002, and to the equalizer 1003. Thereafter, the estimatedinitial frequency offset is outputted to the carrier recovery unit 1090.At this point, the known sequence detector and initial frequency offsetestimator 1004-1 may either receive the output of the matched filter1060 or receive the output of the resampler 1040. This may be optionallydecided depending upon the design of the system designer. Herein, thefrequency offset estimator shown in FIG. 35 may be directly applied inthe known sequence detector and initial frequency offset estimator1004-1 or in the phase compensator 1110 of the frequency offsetestimator.

FIG. 36 illustrates a detailed block diagram showing a known sequencedetector and initial frequency offset estimator according to anembodiment of the present invention. More specifically, FIG. 36illustrates an example of an initial frequency offset being estimatedalong with the known sequence position indicator. Herein, FIG. 36 showsan example of an inputted signal being oversampled to N times of itsinitial state. In other words, N represents the sampling rate of areceived signal. Referring to FIG. 36, the known sequence detector andinitial frequency offset estimator includes N number of partialcorrelators 1411 to 141N configured in parallel, a known data placedetector and frequency offset decider 1420, a known data extractor 1930,a buffer 1940, a multiplier 1450, a NCO 1460, a frequency offsetestimator 1470, and an adder 1480. Herein, the first partial correlator1411 consists of a 1/N decimator, and a partial correlator. The secondpartial correlator 1412 consists of a 1 sample delay, a 1/N decimator,and a partial correlator. And, the N^(th) partial correlator 141Nconsists of a N−1 sample delay, a 1/N decimator, and a partialcorrelator. These are used to match (or identify) the phase of each ofthe samples within the oversampled symbol with the phase of the original(or initial) symbol, and to decimate the samples of the remainingphases, thereby performing partial correlation on each sample. Morespecifically, the input signal is decimated at a rate of 1/N for eachsampling phase, so as to pass through each partial correlator.

For example, when the input signal is oversampled to 2 times (i.e., whenN=2), this indicates that two samples are included in one signal. Inthis case, two partial correlators (e.g., 1911 and 1412) are required,and each 1/N decimator becomes a ½ decimator. At this point, the 1/Ndecimator of the first partial correlator 1411 decimates (or removes),among the input samples, the samples located in-between symbol places(or positions). Then, the corresponding 1/N decimator outputs thedecimated sample to the partial correlator. Furthermore, the 1 sampledelay of the second partial correlator 1412 delays the input sample bysample (i.e., performs a 1 sample delay on the input sample) and outputsthe delayed input sample to the 1/N decimator. Subsequently, among thesamples inputted from the sample delay, the 1/N decimator of the secondpartial correlator 1412 decimates (or removes) the samples locatedin-between symbol places (or positions). Thereafter, the corresponding1/N decimator outputs the decimated sample to the partial correlator.

After each predetermined period of the VSB symbol, each of the partialcorrelators outputs a correlation value and an estimation value of thecoarse frequency offset estimated at that particular moment to the knowndata place detector and frequency offset decider 1420. The known dataplace detector and frequency offset decider 1420 stores the output ofthe partial correlators corresponding to each sampling phase during adata group cycle or a pre-decided cycle. Thereafter, the known dataplace detector and frequency offset decider 1420 decides a position (orplace) corresponding to the highest correlation value, among the storedvalues, as the place (or position) for receiving the known data.Simultaneously, the known data place detector and frequency offsetdecider 1420 finally decides the estimation value of the frequencyoffset estimated at the moment corresponding to the highest correlationvalue as the coarse frequency offset value of the receiving system. Atthis point, the known sequence position indicator is inputted to theknown data extractor 1430, the timing recovery unit 1080, the carrierrecovery unit 1090, the phase compensator 1110, and the equalizer 1003,and the coarse frequency offset is inputted to the adder 1480 and theNCO 1460.

In the meantime, while the N numbers of partial correlators 1411 to 141Ndetect the known data place (or known sequence position) and estimatethe coarse frequency offset, the buffer 1440 temporarily stores thereceived data and outputs the temporarily stored data to the known dataextractor 1430. The known data extractor 1430 uses the known sequenceposition indicator, which is outputted from the known data placedetector and frequency offset decider 1420, so as to extract the knowndata from the output of the buffer 1440. Thereafter, the known dataextractor 1430 outputs the extracted data to the multiplier 1450. TheNCO 1460 generates a complex signal corresponding to the coarsefrequency offset being outputted from the known data place detector andfrequency offset decider 1420. Then, the NCO 1460 outputs the generatedcomplex signal to the multiplier 1450.

The multiplier 1450 multiplies the complex signal of the NCO 1460 to theknown data being outputted from the known data extractor 1430, therebyoutputting the known data having the coarse frequency offset compensatedto the frequency offset estimator 1470. The frequency offset estimator1470 estimates a fine frequency offset from the known data having thecoarse frequency offset compensated. Subsequently, the frequency offsetestimator 1470 outputs the estimated fine frequency offset to the adder1480. The adder 1480 adds the coarse frequency offset to the finefrequency offset. Thereafter, the adder 1480 decides the added result asa final initial frequency offset, which is then outputted to the adder1095 of the carrier recovery unit 1090 included in the demodulator 1002.More specifically, during the process of acquiring initialsynchronization, the present invention may estimate and use the coarsefrequency offset as well as the fine frequency offset, thereby enhancingthe estimation performance of the initial frequency offset.

It is assumed that the known data is inserted within the data group andthen transmitted, as shown in FIG. 5. Then, the known sequence detectorand initial frequency offset estimator 1004-1 may use the known datathat have been additionally inserted between the A1 area and the A2area, so as to estimate the initial frequency offset. The known positionindicator, which was periodically inserted within the A area estimatedby the known sequence detector and initial frequency offset estimator1004-1, is inputted to the timing error detector 1083 of the timingerror recovery unit 1080, to the frequency offset estimator 1092 of thecarrier recovery unit 1090, to the frequency offset estimator 1112 ofthe phase compensator 1110, and to the equalizer 1003.

FIG. 37 illustrates a block diagram showing the structure of one of thepartial correlators shown in FIG. 36. During the step of detecting knowndata, since a frequency offset is included in the received signal, eachpartial correlator divides the known data, which is known according toan agreement between the transmitting system and the receiving system,to K number of parts each having an L symbol length, thereby correlatingeach divided part with the corresponding part of the received signal. Inorder to do so, each partial correlator includes K number of phase andsize detector 1511 to 151K each formed in parallel, an adder 1520, and acoarse frequency offset estimator 1530.

The first phase and size detector 1511 includes an L symbol buffer1511-2, a multiplier 1511-3, an accumulator 1511-4, and a squarer1511-5. Herein, the first phase and size detector 1511 calculates thecorrelation value of the known data having a first L symbol length amongthe K number of sections. Also, the second phase and size detector 1512includes an L symbol delay 1512-1, an L symbol buffer 1512-2, amultiplier 1512-3, an accumulator 1512-4, and a squarer 1512-5. Herein,the second phase and size detector 1512 calculates the correlation valueof the known data having a second L symbol length among the K number ofsections. Finally, the N phase and size detector 151K includes a (K−1)Lsymbol delay 151K−1, an L symbol buffer 151K−2, a multiplier 151K−3, anaccumulator 151K−4, and a squarer 151K−5. Herein, the N^(th) phase andsize detector 151K calculates the correlation value of the known datahaving an N^(th) L symbol length among the K number of sections.

Referring to FIG. 37, {P₀, P₁, . . . , P_(KL−1)} each being multipliedwith the received signal in the multiplier represents the known dataknown by both the transmitting system and the receiving system (i.e.,the reference known data generated from the receiving system). And, *represents a complex conjugate. For example, in the first phase and sizedetector 1511, the signal outputted from the 1/N decimator of the firstpartial correlator 1411, shown in FIG. 36, is temporarily stored in theL symbol buffer 1511-2 of the first phase and size detector 1511 andthen inputted to the multiplier 1511-3. The multiplier 1511-3 multipliesthe output of the L symbol buffer 1511-2 with the complex conjugate ofthe known data parts P₀, P₁, . . . , P_(KL−1) each having a first Lsymbol length among the known K number of sections. Then, the multipliedresult is outputted to the accumulator 1511-4. During the L symbolperiod, the accumulator 1511-4 accumulates the output of the multiplier1511-3 and, then, outputs the accumulated value to the squarer 1511-5and the coarse frequency offset estimator 1530. The output of theaccumulator 1511-4 is a correlation value having a phase and a size.Accordingly, the squarer 1511-5 calculates an absolute value of theoutput of the multiplier 1511-4 and squares the calculated absolutevalue, thereby obtaining the size of the correlation value. The obtainedsize is then inputted to the adder 1520.

The adder 1520 adds the output of the squares corresponding to each sizeand phase detector 1511 to 151K. Then, the adder 1520 outputs the addedresult to the known data place detector and frequency offset decider1420. Also, the coarse frequency offset estimator 1530 receives theoutput of the accumulator corresponding to each size and phase detector1511 to 151K, so as to estimate the coarse frequency offset at eachcorresponding sampling phase. Thereafter, the coarse frequency offsetestimator 1530 outputs the estimated offset value to the known dataplace detector and frequency offset decider 1420.

When the K number of inputs that are outputted from the accumulator ofeach phase and size detector 1511 to 151K are each referred to as {Z₀,Z₁, . . . , Z_(K+1)}, the output of the coarse frequency offsetestimator 1530 may be obtained by using Equation 6 shown below.

$\begin{matrix}{\omega_{0} = {\frac{1}{L}\arg \{ {\sum\limits_{n = 1}^{K - 1}\; {( \frac{Z_{n}}{Z_{n}} )( \frac{Z_{n - 1}}{Z_{n - 1}} )^{*}}} \}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

The known data place detector and frequency offset decider 1420 storesthe output of the partial correlator corresponding to each samplingphase during an enhanced data group cycle or a pre-decided cycle. Then,among the stored correlation values, the known data place detector andfrequency offset decider 1420 decides the place (or position)corresponding to the highest correlation value as the place forreceiving the known data.

Furthermore, the known data place detector and frequency offset decider1420 decides the estimated value of the frequency offset taken (orestimated) at the point of the highest correlation value as the coarsefrequency offset value of the receiving system. For example, if theoutput of the partial correlator corresponding to the second partialcorrelator 1412 is the highest value, the place corresponding to thehighest value is decided as the known data place. Thereafter, the coarsefrequency offset estimated by the second partial correlator 1412 isdecided as the final coarse frequency offset, which is then outputted tothe demodulator 1002.

Meanwhile, the output of the second multiplier 1050 is temporarilystored in the decimator 1081 and the buffer 1082 both included in thetiming recovery unit 1080. Subsequently, the temporarily stored outputdata are inputted to the timing error detector 1083 through thedecimator 1081 and the buffer 1082. Assuming that the output of thesecond multiplier 1050 is oversampled to N times its initial state, thedecimator 1081 decimates the output of the second multiplier 1050 at adecimation rate of 1/N. Then, the 1/N-decimated data are inputted to thebuffer 1082. In other words, the decimator 1081 performs decimation onthe input signal in accordance with a VSB symbol cycle. Furthermore, thedecimator 1081 may also receive the output of the matched filter 1060instead of the output of the second multiplier 1050.

The timing error detector 1083 uses the data prior to or after beingprocessed with matched-filtering and the known sequence positionindicator outputted from the known data detector and initial frequencyoffset estimator 1004-1 in order to detect a timing error. Thereafter,the detected timing error is outputted to the loop filter 1084.Accordingly, the detected timing error information is obtained onceduring each repetition cycle of the known data sequence.

For example, if a known data sequence having the same pattern isperiodically inserted and transmitted, as shown in FIG. 37, the timingerror detector 1083 may use the known data in order to detect the timingerror. There exists a plurality of methods for detecting timing error byusing the known data.

In the example of the present invention, the timing error may bedetected by using a correlation characteristic between the known dataand the received data in the time domain, the known data being alreadyknown in accordance with a pre-arranged agreement between thetransmitting system and the receiving system. The timing error may alsobe detected by using the correlation characteristic of the two knowndata types being received in the frequency domain. Thus, the detectedtiming error is outputted. In another example, a spectral lining methodmay be applied in order to detect the timing error. Herein, the spectrallining method corresponds to a method of detecting timing error by usingsidebands of the spectrum included in the received signal.

The loop filter 1084 filters the timing error detected by the timingerror detector 1083 and, then, outputs the filtered timing error to theholder 1085.

The holder 1085 holds (or maintains) the timing error filtered andoutputted from the loop filter 1084 during a pre-determined known datasequence cycle period and outputs the processed timing error to the NCO1086. Herein, the order of positioning of the loop filter 1084 and theholder 1085 may be switched with one another. In additionally, thefunction of the holder 1085 may be included in the loop filter 1084,and, accordingly, the holder 1085 may be omitted.

The NCO 1086 accumulates the timing error outputted from the holder1085. Thereafter, the NCO 1086 outputs the phase element (i.e., asampling clock) of the accumulated timing error to the resampler 1040,thereby adjusting the sampling timing of the resampler 1040.

FIG. 38 illustrates an example of the timing recovery unit included inthe demodulator 1002 shown in FIG. 36. Referring to FIG. 38, the timingrecovery unit 1080 includes a first timing error detector 1611, a secondtiming error detector 1612, a multiplexer 1613, a loop-filter 1614, andan NCO 1615. The timing recovery unit 1080 would be beneficial when theinput signal is divided into a first area in which known data having apredetermined length are inserted at predetermined position(s) and asecond area that includes no known data. Assuming that the first timingerror detector 1611 detects a first timing error using a sideband of aspectrum of an input signal and the second timing error detector 1612detects a second timing error using the known data, the multiplexer 1613can output the first timing error for the first area and can output thesecond timing error for the second area. The multiplexer 1613 may outputboth of the first and second timing errors for the first area in whichthe known data are inserted. By using the known data a more reliabletiming error can be detected and the performance of the timing recoveryunit 1080 can be enhanced.

This disclosure describes two ways of detecting a timing error. One wayis to detect a timing error using correlation in the time domain betweenknown data pre-known to a transmitting system and a receiving system(reference known data) and the known data actually received by thereceiving system, and the other way is to detect a timing error usingcorrelation in the frequency domain between two known data actuallyreceived by the receiving system. In FIG. 39, a timing error is detectedby calculating correlation between the reference known data pre-known toand generated by the receiving system and the known data actuallyreceived. In FIG. 39, correlation between an entire portion of thereference know data sequence and an entire portion of the received knowndata sequence is calculated. The correlation output has a peak value atthe end of each known data sequence actually received.

In FIG. 40, a timing error is detected by calculating correlation valuesbetween divided portions of the reference known data sequence anddivided portions of the received known data sequence, respectively. Thecorrelation output has a peak value at the end of each divided portionof the received known data sequence. The correlation values may be addedas a total correlation value as shown FIG. 40, and the total correlationvalue can be used to calculate the timing error. When an entire portionof the received known data is used for correlation calculation, thetiming error can be obtained for each data block. If the correlationlevel of the entire portion of the known data sequence is low, a moreprecise correlation can be obtained by using divided portions of theknown data sequence as shown in FIG. 40.

The use of a final correlation value which is obtained based upon aplurality of correlation values of divided portions of a received knowndata sequence may reduce the carrier frequency error. In addition, theprocess time for the timing recovery can be greatly reduced when theplurality of correlation values are used to calculate the timing error.For example, when the reference known data sequence which is pre-knownto the transmitting system and receiving system is divided into Kportions, K correlation values between the K portions of the referenceknown data sequence and the corresponding divided portions of thereceived known data sequence can be calculated, or any combination(s) ofthe correlation values can be used. Therefore, the period of the timingerror detection can be reduced when the divided portions of the knowndata sequence are used instead of the entire portion of the sequence.

The timing error can be calculated from the peak value of thecorrelation values. The timing error is obtained for each data block ifan entire portion of the known data sequence is used as shown in FIG.41. On the other hand, if K divided portions of the known data sequenceare used for correlation calculation, K correlation values andcorresponding peak values can be obtained. This indicates that thetiming error can be detected K times.

A method of detecting a timing error using the correlation between thereference known data and the received known data shown will now bedescribed in more detail. FIG. 41 illustrates correlation values betweenthe reference known data and the received known data. The correlationvalues correspond to data samples sampled at a rate two times greaterthan the symbol clock. When the random data effect is minimized andthere is no timing clock error, the correlation values between thereference known data and the received known data are symmetrical.However, if a timing phase error exists, the correlation values adjacentto the peak value are not symmetrical as shown in FIG. 41. Therefore,the timing error can be obtained by using a difference (timing phaseerror shown in FIG. 41) between the correlation values before and afterthe peak value.

FIG. 42 illustrates an example of the timing error detector shown inFIG. 38. The timing error detector includes a correlator 1701, a downsampler 1702, an absolute value calculator 1703, a delay 1704, and asubtractor 1705. The correlator 1701 receives a known data sequencesampled at a rate at least two times higher than the symbol clockfrequency and calculates the correlation values between the receivedknown data sequence and a reference known data sequence. The downsampler 1702 performs down sampling on the correlation values andobtains samples having a symbol frequency. For example, if the datainputted to the correlator 1701 is pre-sampled at a sampling rate of 2,then the down sampler 1702 performs down sampling at a rate of ½ toobtain samples having the symbol frequency. The absolute valuecalculator 1703 calculates absolute values (or square values) of thedown-sampled correlation values. These absolute values are inputted tothe delay 1704 and the subtractor 1705. The delay 1704 delays theabsolute values for a symbol and the subtractor then outputs a timingerror by subtracting the delayed absolute value from the valuesoutputted from the absolute value calculator 1703.

The arrangement of the correlator 1701, the down sampler 1702, theabsolute value calculator 1703, and the delay 1704, and the subtractor1705 shown in FIG. 42 can be modified. For example, the timing phaseerror can be calculated in the order of the down sampler 1702, thecorrelator 1701, and the absolute value calculator 1703, or in the orderof the correlator 1701, the absolute value calculator 1703, and the downsampler 1702.

The timing error can also be obtained using the frequency characteristicof the known data. When there is a timing frequency error, a phase ofthe input signal increases at a fixed slope as the frequency of thesignal increases and this slope is different for current and next datablock. Therefore, the timing error can be calculated based on thefrequency characteristic of two different known data blocks. In FIG. 43,a current known data sequence (right) and a previous known data sequence(left) are converted into first and second frequency domain signals,respectively, using a Fast Fourier Transform (FFT) algorithm. Theconjugate value of the first frequency domain signal is then multipliedwith the second frequency domain signal in order to obtain thecorrelation value between two frequency domain signals. In other words,the correlation between the frequency value of the previous known datasequence and the frequency value of the current known data sequence isused to detect a phase change between the known data blocks for eachfrequency. In this way the phase distortion of a channel can beeliminated.

The frequency response of a complex VSB signal does not have a fullsymmetric distribution as shown in FIG. 41. Rather, its distribution isa left or right half of the distribution and the frequency domaincorrelation values also have a half distribution. In order to the phasedifference between the frequency domain correlation values, thefrequency domain having the correlation values can be divided into twosub-areas and a phase of a combined correlation value in each sub-areacan be obtained. Thereafter, the difference between the phases ofsub-areas can be used to calculate a timing frequency error. When aphase of a combined correlation values is used for each frequency, themagnitude of each correlation value is proportional to reliability and aphase component of each correlation value is reflected to the finalphase component in proportion to the magnitude.

FIG. 44 illustrates another example of the timing error detector shownin FIG. 38. The timing error detector shown in FIG. 44 includes a FastFourier Transform (FFT) unit 1801, a first delay 1802, a conjugator1803, a multiplier 1804, an accumulator (adder) 1805, a phase detector1806, a second delay 1807, and a subtractor 1808. The first delay 1802delays for one data block and the second delay 1807 delays for ¼ datablock. One data block includes a frequency response of a sequence of Nknown data symbol sequences. When a known data region is known and thedata symbols are received, the FFT unit 1801 converts complex values ofconsecutive N known data symbol sequences into complex values in thefrequency domain. The first delay 1802 delays the frequency domaincomplex values for a time corresponding to one data block, and theconjugator 1803 generate conjugate values of the delayed complex values.The multiplier 1804 multiplies the current block of known data outputtedfrom the FFT unit 1801 with the previous block of known data outputtedfrom the conjugator 1803. The output of the multiplier 1804 representsfrequency region correlation values within a known data block.

Since the complex VSB data exist only on a half of the frequency domain,the accumulator 1805 divides a data region in the known data block intotwo sub-regions, and accumulates correlation values for each sub-region.The phase detector 1806 detects a phase of the accumulated correlationvalue for each sub-region. The second delay 1807 delays the detectedphase for a time corresponding to a ¼ data block. The subtractor 1808obtains a phase difference between the delayed phase and the phaseoutputted from the accumulator 1806 and outputs the phase difference asa timing frequency error.

In the method of calculating a timing error by using a peak ofcorrelation between the reference known data and the received known datain the time domain, the contribution of the correlation values mayaffect a channel when the channel is a multi path channel. However, thiscan be greatly eliminated if the timing error is obtained using thecorrelation between two received known data. In addition, the timingerror can be detected using an entire portion of the known data sequenceinserted by the transmitting system, or it can be detected using aportion of the known data sequence which is robust to random or noisedata.

Meanwhile, the DC remover 1070 removes pilot tone signal (i.e., DCsignal), which has been inserted by the transmitting system, from thematched-filtered signal. Thereafter, the DC remover 1070 outputs theprocessed signal to the phase compensator 1110.

FIG. 45 illustrates a detailed block diagram of a DC remover accordingto an embodiment of the present invention. Herein, identical signalprocessing processes are performed on each of a real number element (orin-phase (I)) and an imaginary number element (or a quadrature (Q)) ofthe inputted complex signal, thereby estimating and removing the DCvalue of each element. In order to do so, the DC remover shown in FIG.45 includes a first DC estimator and remover 1900 and a second DCestimator and remover 1950. Herein, the first DC estimator and remover1900 includes an R sample buffer 1901, a DC estimator 1902, an M sampleholder 1903, a C sample delay 1904, and a subtractor 1905. Herein, thefirst DC estimator and remover 1900 estimates and removes the DC of thereal number element (i.e., an in-phase DC). Furthermore, the second DCestimator and remover 1950 includes an R sample buffer 1951, a DCestimator 1952, an M sample holder 1953, a C sample delay 1954, and asubtractor 1955. The second DC estimator and remover 1950 estimates andremoves the DC of the imaginary number element (i.e., a quadrature DC).In the present invention, the first DC estimator and remover 1900 andthe second DC estimator and remover 1950 may receive different inputsignals. However, each DC estimator and remover 1900 and 1950 has thesame structure. Therefore, a detailed description of the first DCestimator and remover 1900 will be presented herein, and the second DCestimator and remover 1950 will be omitted for simplicity.

More specifically, the in-phase signal matched-filtered by the matchedfilter 1060 is inputted to the R sample buffer 1901 of the first DCestimator and remover 1900 within the DC remover 1070 and is thenstored. The R sample buffer 1901 is a buffer having the length of Rsample. Herein, the output of the R sample buffer 1901 is inputted tothe DC estimator 1902 and the C sample delay 1904. The DC estimator 1902uses the data having the length of R sample, which are outputted fromthe buffer 1901, so as to estimate the DC value by using Equation 7shown below.

$\begin{matrix}{{y\lbrack n\rbrack} = {\frac{1}{R}{\sum\limits_{k = 0}^{R - 1}\; {x\lbrack {k + {M*n}} \rbrack}}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

In the above-described Equation 7, x[n] represents the inputted sampledata stored in the buffer 1901. And, y[n] indicates the DC estimationvalue. More specifically, the DC estimator 1902 accumulates R number ofsample data stored in the buffer 1901 and estimates the DC value bydividing the accumulated value by R. At this point, the stored inputsample data set is shifted as much as M sample. Herein, the DCestimation value is outputted once every M samples.

FIG. 46 illustrates a shifting of the input sample data used for DCestimation. For example, when M is equal to 1 (i.e., M=1), the DCestimator 1902 estimates the DC value each time a sample is shifted tothe buffer 1901. Accordingly, each estimated result is outputted foreach sample. If M is equal to R (i.e., M=R), the DC estimator 1902estimates the DC value each time R number of samples are shifted to thebuffer 1901. Accordingly, each estimated result is outputted for eachcycle of R samples. Therefore, in this case, the DC estimator 1902corresponds to a DC estimator that operates in a block unit of Rsamples. Herein, any value within the range of 1 and R may correspond tothe value M.

As described above, since the output of the DC estimator 1902 isoutputted after each cycle of M samples, the M sample holder 1903 holdsthe DC value estimated from the DC estimator 1902 for a period of Msamples. Then, the estimated DC value is outputted to the subtractor1905. Also, the C sample delay 1904 delays the input sample data storedin the buffer 1901 by C samples, which are then outputted to thesubtractor 1905. The subtractor 1905 subtracts the output of the Msample holder 1903 from the output of the C sample delay 1904.Thereafter, the subtractor 1905 outputs the signal having the in-phaseDC removed.

Herein, the C sample delay 1904 decides which portion of the inputsample data is to be compensated with the output of the DC estimator1902. More specifically, the DC estimator and remover 1900 may bedivided into a DC estimator 1902 for estimating the DC and thesubtractor for compensating the input sample data within the estimatedDC value. At this point, the C sample delay 1904 decides which portionof the input sample data is to be compensated with the estimated DCvalue. For example, when C is equal to 0 (i.e., C=0), the beginning ofthe R samples is compensated with the estimated DC value obtained byusing R samples. Alternatively, when C is equal to R (i.e., C=R), theend of the R samples is compensated with the estimated DC value obtainedby using R samples. Similarly, the data having the DC removed areinputted to the buffer 1111 and the frequency offset estimator 1112 ofthe phase compensator 1110.

Meanwhile, FIG. 47 illustrates a detailed block diagram of a DC removeraccording to another embodiment of the present invention. Herein,identical signal processing processes are performed on each of a realnumber element (or in-phase (I)) and an imaginary number element (or aquadrature (Q)) of the inputted complex signal, thereby estimating andremoving the DC value of each element. In order to do so, the DC removershown in FIG. 47 includes a first DC estimator and remover 2100 and asecond DC estimator and remover 2150. FIG. 47 corresponds to an infiniteimpulse response (IIR) structure.

Herein, the first DC estimator and remover 2100 includes a multiplier2101, an adder 2102, an 1 sample delay 2103, a multiplier 2104, a Csample delay 2105, and a subtractor 2106. Also, the second DC estimatorand remover 2150 includes a multiplier 2151, an adder 2152, an 1 sampledelay 2153, a multiplier 2154, a C sample delay 2155, and a subtractor2156. In the present invention, the first DC estimator and remover 2100and the second DC estimator and remover 2150 may receive different inputsignals. However, each DC estimator and remover 2100 and 2150 has thesame structure. Therefore, a detailed description of the first DCestimator and remover 2100 will be presented herein, and the second DCestimator and remover 2150 will be omitted for simplicity.

More specifically, the in-phase signal matched-filtered by the matchedfilter 1060 is inputted to the multiplier 2101 and the C sample delay2105 of the first DC estimator and remover 2100 within the DC remover1070. The multiplier 2101 multiplies a pre-determined constant α to thein-phase signal that is being inputted. Then, the multiplier 2101outputs the multiplied result to the adder 2102. The adder 2102 adds theoutput of the multiplier 2101 to the output of the multiplier 2104 thatis being fed-back. Thereafter, the adder 2102 outputs the added resultto the 1 sample delay 2103 and the subtractor 2106. More specifically,the output of the adder 2102 corresponds to the estimated in-phase DCvalue.

The 1 sample delay 2103 delays the estimated DC value by 1 sample andoutputs the DC value delayed by 1 sample to the multiplier 2104. Themultiplier 2109 multiplies a pre-determined constant (1−α) to the DCvalue delayed by 1 sample. Then, the multiplier 2104 feeds-back themultiplied result to the adder 2102.

Subsequently, the C sample delay 2105 delays the in-phase sample data byC samples and, then, outputs the delayed in-phase sample data to thesubtractor 2106. The subtractor 2106 subtracts the output of the adder2102 from the output of the C sample delay 2105, thereby outputting thesignal having the in-phase DC removed therefrom.

Similarly, the data having the DC removed are inputted to the buffer1111 and the frequency offset estimator 1112 of the phase compensator1110 of FIG. 34.

The frequency offset estimator 1112 uses the known sequence positionindicator outputted from the known sequence detector and initialfrequency offset estimator 1004-1 in order to estimate the frequencyoffset from the known data sequence that is being inputted, the knowndata sequence having the DC removed by the DC remover 1070. Then, thefrequency offset estimator 1112 outputs the estimated frequency offsetto the holder 1113. Similarly, the frequency offset estimation value isobtained at each repetition cycle of the known data sequence.

Therefore, the holder 1113 holds the frequency offset estimation valueduring a cycle period of the known data sequence and then outputs thefrequency offset estimation value to the NCO 1114. The NCO 1114generates a complex signal corresponding to the frequency offset held bythe holder 1113 and outputs the generated complex signal to themultiplier 1115.

The multiplier 1115 multiplies the complex signal outputted from the NCO1114 to the data being delayed by a set period of time in the buffer1111, thereby compensating the phase change included in the delayeddata. The data having the phase change compensated by the multiplier1115 pass through the decimator 1200 so as to be inputted to theequalizer 1003. At this point, since the frequency offset estimated bythe frequency offset estimator 1112 of the phase compensator 1110 doesnot pass through the loop filter, the estimated frequency offsetindicates the phase difference between the known data sequences. Inother words, the estimated frequency offset indicates a phase offset.

Channel Equalizer

The demodulated data using the known data in the demodulator 1002 isinputted to the channel equalizer 1003. The demodulated data is inputtedto the known sequence detector 1004.

The equalizer 1003 may perform channel equalization by using a pluralityof methods. An example of estimating a channel impulse response (CIR) soas to perform channel equalization will be given in the description ofthe present invention. Most particularly, an example of estimating theCIR in accordance with each region within the data group, which ishierarchically divided and transmitted from the transmitting system, andapplying each CIR differently will also be described herein.Furthermore, by using the known data, the place and contents of which isknown in accordance with an agreement between the transmitting systemand the receiving system, and/or the field synchronization data, so asto estimate the CIR, the present invention may be able to performchannel equalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to D, as shown in FIG. 5. More specifically, inthe example of the present invention, each region A, B, C, and D arefurther divided into MPH blocks B4 to B7, MPH blocks B3 and B8, MPHblocks B2 and B9, MPH blocks B1 and B10, respectively.

More specifically, a data group can be assigned and transmitted amaximum the number of 4 in a VSB frame in the transmitting system. Inthis case, all data group do not include field synchronization data. Inthe present invention, the data group including the fieldsynchronization data performs channel-equalization using the fieldsynchronization data and known data. And the data group not includingthe field synchronization data performs channel-equalization using theknown data. For example, the data of the MPH block B3 including thefield synchronization data performs channel-equalization using the CIRcalculated from the field synchronization data area and the CIRcalculated from the first known data area. Also, the data of the MPHblocks B1 and B2 performs channel-equalization using the CIR calculatedfrom the field synchronization data area and the CIR calculated from thefirst known data area. Meanwhile, the data of the MPH blocks B4 to B6not including the field synchronization data performschannel-equalization using CIRS calculated from the first known dataarea and the third known data area.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

FIG. 48 is a flow chart illustrating a channel equalization methodaccording to one aspect of the present invention. An input data group(current data group) is temporarily stored (2301), and CIRs of the fieldsync data and the known data sequences included in the stored data groupare estimated (2302). In step 2301, a portion of the data group can bestored, because regions B1, C1, and A1 are received before the firstknown data region and the channel equalization for regions B1, C1, andA1 are performed using a CIR estimated from the first known data region.

In step 2303, the channel equalization for region C1 of a current datagroup may be performed using a CIR which is estimated by extrapolatingCIR_FS and CIR_N0 estimated from the current data group. Alternatively,the channel equalization for region C1 of the current data group can beperformed using any one of CIR_N4 estimated from a previous data groupand CIR_FS estimated from the current data group. If the extrapolatedCIR is used, the data included in region C1 must be stored until CIR_N0is estimated because the region C1 data are inputted before the firstknown data region in the current group. The data included in region C1can be stored in a memory in the broadcast receiving system, or in anexternal storage.

In step 2303, the channel equalization for region B1 of a current datagroup may be performed using a CIR which is estimated by extrapolatingCIR_FS and CIR_N0 estimated from the current data group. In furtherexample, the channel equalization for region B1 can be performed usingCIR_FS of the current data group. Similarly, the data included in theregion B1 must be stored until CIR_N0 (or CIR_FS) is estimated becausethe B1 region data are inputted before the first known data region. Thedata included in region B1 can be stored in a memory in the broadcastreceiving system, or in an external storage,

In step 2304, the channel equalization for region A1 of a current datagroup may be performed using a CIR which is estimated by interpolatingCIR_FS and CIR_N0 estimated from the current data group. Alternatively,the channel equalization for region A1 can be performed using any one ofCIR_FS and CIR_N0 estimated from the currently data group. If region A1is equalized using the interpolated CIR, the data included in region A1must be stored until CIR_N0 (or CIR_FS) is estimated. The data includedin region A1 can be stored in a memory in the broadcast receivingsystem, or in an external storage.

For Ai, (i=2, 3, 4, and 5) of a current data group, the channelequalization may be performed using a CIR which is estimated byinterpolating CIR_N (i−1) and CIR_N(i) of the current data group (2305).Alternatively, the channel equalization for Ai may be performed usingany one of CIR_N(i−1) and CIR_N(i). For example, channel equalizationfor A2 (i=2) is performed using a CIR estimated by interpolating CIR_N1and CIR_N2 of the current data group or using any one of CIR_N1 andCIR_N2 of the current data group.

In step 2306, the channel equalization for regions B2, C2, and C3 may beperformed using a CIR estimated by interpolating CIR_N3 and CIR_N4estimated from the current data group. Alternatively, the channelequalization may be performed using CIR_N4 estimated from the currentdata group.

FIG. 49 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. Herein, by estimating andcompensating a remaining carrier phase error from a channel-equalizedsignal, the receiving system of the present invention may be enhanced.Referring to FIG. 49, the channel equalizer includes a first frequencydomain converter 3100, a channel estimator 3110, a second frequencydomain converter 3121, a coefficient calculator 3122, a distortioncompensator 3130, a time domain converter 3140, a remaining carrierphase error remover 3150, a noise canceller (NC) 3160, and a decisionunit 3170.

Herein, the first frequency domain converter 3100 includes an overlapunit 3101 overlapping inputted data, and a fast fourier transform (FFT)unit 3102 converting the data outputted from the overlap unit 3101 tofrequency domain data.

The channel estimator 3110 includes a CIR estimator, a phase compensator3112, a pre-CIR cleaner 3113, CIR interpolator/extrapolator 3114, apost-CIR cleaner, and a zero-padding unit.

The second frequency domain converter 3121 includes a fast fouriertransform (FFT) unit converting the CIR being outputted from the channelestimator 3110 to frequency domain CIR.

The time domain converter 3140 includes an IFFT unit 3141 converting thedata having the distortion compensated by the distortion compensator3130 to time domain data, and a save unit 3142 extracting only validdata from the data outputted from the IFFT unit 3141.

The remaining carrier phase error remover 3150 includes an errorcompensator 3151 removing the remaining carrier phase error included inthe channel equalized data, and a remaining carrier phase errorestimator 3152 using the channel equalized data and the decision data ofthe decision unit 3170 so as to estimate the remaining carrier phaseerror, thereby outputting the estimated error to the error compensator3151. Herein, any device performing complex number multiplication may beused as the distortion compensator 3130 and the error compensator 3151.

At this point, since the received data correspond to data modulated toVSB type data, 8-level scattered data exist only in the real numberelement. Therefore, referring to FIG. 49, all of the signals used in thenoise canceller 3160 and the decision unit 3170 correspond to realnumber (or in-phase) signals. However, in order to estimate andcompensate the remaining carrier phase error and the phase noise, bothreal number (in-phase) element and imaginary number (quadrature) elementare required. Therefore, the remaining carrier phase error remover 3150receives and uses the quadrature element as well as the in-phaseelement. Generally, prior to performing the channel equalizationprocess, the demodulator 902 within the receiving system performsfrequency and phase recovery of the carrier. However, if a remainingcarrier phase error that is not sufficiently compensated is inputted tothe channel equalizer, the performance of the channel equalizer may bedeteriorated. Particularly, in a dynamic channel environment, theremaining carrier phase error may be larger than in a static channelenvironment due to the frequent and sudden channel changes. Eventually,this acts as an important factor that deteriorates the receivingperformance of the present invention.

Furthermore, a local oscillator (not shown) included in the receivingsystem should preferably include a single frequency element. However,the local oscillator actually includes the desired frequency elements aswell as other frequency elements. Such unwanted (or undesired) frequencyelements are referred to as phase noise of the local oscillator. Suchphase noise also deteriorates the receiving performance of the presentinvention. It is difficult to compensate such remaining carrier phaseerror and phase noise from the general channel equalizer. Therefore, thepresent invention may enhance the channel equaling performance byincluding a carrier recovery loop (i.e., a remaining carrier phase errorremover 3150) in the channel equalizer, as shown in FIG. 49, in order toremove the remaining carrier phase error and the phase noise.

More specifically, the receiving data demodulated in FIG. 49 areoverlapped by the overlap unit 3101 of the first frequency domainconverter 3100 at a pre-determined overlapping ratio, which are thenoutputted to the FFT unit 3102. The FFT unit 3102 converts theoverlapped time domain data to overlapped frequency domain data throughby processing the data with FFT. Then, the converted data are outputtedto the distortion compensator 3130.

The distortion compensator 3130 performs a complex number multiplicationon the overlapped frequency domain data outputted from the FFT unit 3102included in the first frequency domain converter 3100 and theequalization coefficient calculated from the coefficient calculator3122, thereby compensating the channel distortion of the overlapped dataoutputted from the FFT unit 3102. Thereafter, the compensated data areoutputted to the IFFT unit 3141 of the time domain converter 3140. TheIFFT unit 3141 performs IFFT on the overlapped data having the channeldistortion compensated, thereby converting the overlapped data to timedomain data, which are then outputted to the error compensator 3151 ofthe remaining carrier phase error remover 3150.

The error compensator 3151 multiplies a signal compensating theestimated remaining carrier phase error and phase noise with the validdata extracted from the time domain. Thus, the error compensator 3151removes the remaining carrier phase error and phase noise included inthe valid data.

The data having the remaining carrier phase error compensated by theerror compensator 3151 are outputted to the remaining carrier phaseerror estimator 3152 in order to estimate the remaining carrier phaseerror and phase noise and, at the same time, outputted to the noisecanceller 3160 in order to remove (or cancel) the noise.

The remaining carrier phase error estimator 3152 uses the output data ofthe error compensator 3151 and the decision data of the decision unit3170 to estimate the remaining carrier phase error and phase noise.Thereafter, the remaining carrier phase error estimator 3152 outputs asignal for compensating the estimated remaining carrier phase error andphase noise to the error compensator 3151. In this embodiment of thepresent invention, an inverse number of the estimated remaining carrierphase error and phase noise is outputted as the signal for compensatingthe remaining carrier phase error and phase noise.

FIG. 50 illustrates a detailed block diagram of the remaining carrierphase error estimator 3152 according to an embodiment of the presentinvention. Herein, the remaining carrier phase error estimator 3152includes a phase error detector 3211, a loop filter 3212, a numericallycontrolled oscillator (NCO) 3213, and a conjugator 3214. Referring toFIG. 50, the decision data, the output of the phase error detector 3211,and the output of the loop filter 3212 are all real number signals. And,the output of the error compensator 3151, the output of the NCO 3213,and the output of the conjugator 3214 are all complex number signals.

The phase error detector 3211 receives the output data of the errorcompensator 3151 and the decision data of the decision unit 3170 inorder to estimate the remaining carrier phase error and phase noise.Then, the phase error detector 3211 outputs the estimated remainingcarrier phase error and phase noise to the loop filter.

The loop filter 3212 then filters the remaining carrier phase error andphase noise, thereby outputting the filtered result to the NCO 3213. TheNCO 3213 generates a cosine corresponding to the filtered remainingcarrier phase error and phase noise, which is then outputted to theconjugator 3214.

The conjugator 3214 calculates the conjugate value of the cosine wavegenerated by the NCO 3213. Thereafter, the calculated conjugate value isoutputted to the error compensator 3151. At this point, the output dataof the conjugator 3214 becomes the inverse number of the signalcompensating the remaining carrier phase error and phase noise. In otherwords, the output data of the conjugator 3214 becomes the inverse numberof the remaining carrier phase error and phase noise.

The error compensator 3151 performs complex number multiplication on theequalized data outputted from the time domain converter 3140 and thesignal outputted from the conjugator 3214 and compensating the remainingcarrier phase error and phase noise, thereby removing the remainingcarrier phase error and phase noise included in the equalized data.Meanwhile, the phase error detector 3211 may estimate the remainingcarrier phase error and phase noise by using diverse methods andstructures. According to this embodiment of the present invention, theremaining carrier phase error and phase noise are estimated by using adecision-directed method.

If the remaining carrier phase error and phase noise are not included inthe channel-equalized data, the decision-directed phase error detectoraccording to the present invention uses the fact that only real numbervalues exist in the correlation values between the channel-equalizeddata and the decision data. More specifically, if the remaining carrierphase error and phase noise are not included, and when the input data ofthe phase error detector 3211 are referred to as x_(i)+jx_(q), thecorrelation value between the input data of the phase error detector3211 and the decision data may be obtained by using Equation 8 shownbelow:

E{(x _(i) +jx _(q))({circumflex over (x)} _(i) +j{circumflex over (x)}_(q))*}  Equation 8

At this point, there is no correlation between x_(i) and x_(q).Therefore, the correlation value between x_(i) and x_(q) is equal to 0.Accordingly, if the remaining carrier phase error and phase noise arenot included, only the real number values exist herein. However, if theremaining carrier phase error and phase noise are included, the realnumber element is shown in the imaginary number value, and the imaginarynumber element is shown in the real number value. Thus, in this case,the imaginary number element is shown in the correlation value.Therefore, it can be assumed that the imaginary number portion of thecorrelation value is in proportion with the remaining carrier phaseerror and phase noise. Accordingly, as shown in Equation 9 below, theimaginary number of the correlation value may be used as the remainingcarrier phase error and phase noise.

Phase Error=imag{(x _(i) +jx _(q))({circumflex over (x)} _(i)+j{circumflex over (x)} _(q))*}

Phase Error=x _(q) {circumflex over (x)} _(i) −x _(i) {circumflex over(x)} _(q)  Equation 9

FIG. 51 illustrates a block diagram of a phase error detector 3211obtaining the remaining carrier phase error and phase noise. Herein, thephase error detector 3211 includes a Hilbert converter 3311, a complexnumber configurator 3312, a conjugator 3313, a multiplier 3314, and aphase error output 3315. More specifically, the Hilbert converter 3311creates an imaginary number decision data {circumflex over (x)}_(q) byperforming a Hilbert conversion on the decision value {circumflex over(x)}_(i) of the decision unit 3170. The generated imaginary numberdecision value is then outputted to the complex number configurator3312. The complex number configurator 3312 uses the decision data{circumflex over (x)}_(i) and {circumflex over (x)}_(q) to configure thecomplex number decision data {circumflex over (x)}_(i)+j{circumflex over(x)}_(g), which are then outputted to the conjugator 3313. Theconjugator 3313 conjugates the output of the complex number configurator3312, thereby outputting the conjugated value to the multiplier 3314.The multiplier 3314 performs a complex number multiplication on theoutput data of the error compensator 3151 and the output data{circumflex over (x)}_(i)−j{circumflex over (x)}_(q) of the conjugator3313, thereby obtaining the correlation between the output datax_(i)+jx_(q) of the error compensator 3151 and the decision value{circumflex over (x)}_(i)−j{circumflex over (x)}_(q) of the decisionunit 3170. The correlation data obtained from the multiplier 3314 arethen inputted to the phase error output 3315. The phase error output3315 outputs the imaginary number portion x_(q){circumflex over(x)}_(i)−x_(i){circumflex over (x)}_(q) of the correlation dataoutputted from the multiplier 3314 as the remaining carrier phase errorand phase noise.

The phase error detector shown in FIG. 51 is an example of a pluralityof phase error detecting methods. Therefore, other types of phase errordetectors may be used in the present invention. Therefore, the presentinvention is not limited only to the examples and embodiments presentedin the description of the present invention. Furthermore, according toanother embodiment of the present invention, at least 2 phase errordetectors are combined so as to detect the remaining carrier phase errorand phase noise.

Accordingly, the output of the remaining carrier phase error remover3150 having the detected remaining carrier phase error and phase noiseremoved as described above, is configured of an addition of the original(or initial) signal having the channel equalization, the remainingcarrier phase error and phase noise, and the signal corresponding to awhite noise being amplified to a colored noise during the channelequalization.

Therefore, the noise canceller 3160 receives the output data of theremaining carrier phase error remover 3150 and the decision data of thedecision unit 3170, thereby estimating the colored noise. Then, thenoise canceller 3160 subtracts the estimated colored noise from the datahaving the remaining carrier phase error and phase noise removedtherefrom, thereby removing the noise amplified during the equalizationprocess.

In order to do so, the noise canceller 3160 includes a subtractor and anoise predictor. More specifically, the subtractor subtracts the noisepredicted by the noise predictor from the output data of the residualcarrier phase error estimator 3150. Then, the subtractor outputs thesignal from which amplified noise is cancelled (or removed) for datarecovery and, simultaneously, outputs the same signal to the decisionunit 3170. The noise predictor calculates a noise element by subtractingthe output of the decision unit 3170 from the signal having residualcarrier phase error removed therefrom by the residual carrier phaseerror estimator 3150. Thereafter, the noise predictor uses thecalculated noise element as input data of a filter included in the noisepredictor. Also, the noise predictor uses the filter (not shown) inorder to predict any color noise element included in the output symbolof the residual carrier phase error estimator 3150. Accordingly, thenoise predictor outputs the predicted color noise element to thesubtractor.

The data having the noise removed (or cancelled) by the noise canceller3160 are outputted for the data decoding process and, at the same time,outputted to the decision unit 3170.

The decision unit 3170 selects one of a plurality of pre-determineddecision data sets (e.g., 8 decision data sets) that is most approximateto the output data of the noise canceller 3160, thereby outputting theselected data to the remaining carrier phase error estimator 3152 andthe noise canceller 3160.

Meanwhile, the received data are inputted to the overlap unit 3101 ofthe first frequency domain converter 3100 included in the channelequalizer and, at the same time, inputted to the CIR estimator 3111 ofthe channel estimator 3110.

The CIR estimator 3111 uses a training sequence, for example, data beinginputted during the known data section and the known data in order toestimate the CIR, thereby outputting the estimated CIR to the phasecompensator 3112. If the data to be channel-equalizing is the datawithin the data group including field synchronization data, the trainingsequence using in the CIR estimator 3111 may become the fieldsynchronization data and known data. Meanwhile, if the data to bechannel-equalizing is the data within the data group not including fieldsynchronization data, the training sequence using in the CIR estimator3111 may become only the known data.

For example, the CIR estimator 3111 estimates CIR using the known datacorrespond to reference known data generated during the known datasection by the receiving system in accordance with an agreement betweenthe receiving system and the transmitting system. For this, the CIRestimator 3111 is provided known data position information from theknown sequence detector 1004. Also the CIR estimator 3111 may beprovided field synchronization position information from the knownsequence detector 1004.

Furthermore, in this embodiment of the present invention, the CIRestimator 3111 estimates the CIR by using the least square (LS) method.

The LS estimation method calculates a cross correlation value p betweenthe known data that have passed through the channel during the knowndata section and the known data that are already known by the receivingend. Then, a cross correlation matrix R of the known data is calculated.Subsequently, a matrix operation is performed on R⁻¹·p so that the crosscorrelation portion within the cross correlation value p between thereceived data and the initial known data, thereby estimating the CIR ofthe transmission channel.

The phase compensator 3112 compensates the phase change of the estimatedCIR. Then, the phase compensator 3112 outputs the compensated CIR to thelinear interpolator 3113. At this point, the phase compensator 3112 maycompensate the phase change of the estimated CIR by using a maximumlikelihood method.

More specifically, the remaining carrier phase error and phase noisethat are included in the demodulated received data and, therefore, beinginputted change the phase of the CIR estimated by the CIR estimator 3111at a cycle period of one known data sequence. At this point, if thephase change of the inputted CIR, which is to be used for the linearinterpolation process, is not performed in a linear form due to a highrate of the phase change, the channel equalizing performance of thepresent invention may be deteriorated when the channel is compensated bycalculating the equalization coefficient from the CIR, which isestimated by a linear interpolation method.

Therefore, the present invention removes (or cancels) the amount ofphase change of the CIR estimated by the CIR estimator 3111 so that thedistortion compensator 3130 allows the remaining carrier phase error andphase noise to bypass the distortion compensator 3130 without beingcompensated. Accordingly, the remaining carrier phase error and phasenoise are compensated by the remaining carrier phase error remover 3150.

For this, the present invention removes (or cancels) the amount of phasechange of the CIR estimated by the phase compensator 3112 by using amaximum likelihood method.

The basic idea of the maximum likelihood method relates to estimating aphase element mutually (or commonly) existing in all CIR elements, thento multiply the estimated CIR with an inverse number of the mutual (orcommon) phase element, so that the channel equalizer, and mostparticularly, the distortion compensator 3130 does not compensate themutual phase element.

More specifically, when the mutual phase element is referred to as θ,the phase of the newly estimated CIR is rotated by θ as compared to thepreviously estimated CIR. When the CIR of a point t is referred to ash_(i)(t), the maximum likelihood phase compensation method obtains aphase θ_(ML) corresponding to when h_(i)(t) is rotated by θ, the squaredvalue of the difference between the CIR of h_(i)(t) and the CIR ofh_(i)(t+1), i.e., the CIR of a point (t+1), becomes a minimum value.Herein, when i represents a tap of the estimated CIR, and when Nrepresents a number of taps of the CIR being estimated by the CIRestimator 3111, the value of θ_(ML) is equal to or greater than 0 andequal to or less than N−1. This value may be calculated by usingEquation 10 shown below:

$\begin{matrix}{\theta_{ML} = {\begin{matrix}\min \\\theta\end{matrix}{\sum\limits_{i = 0}^{N - 1}\; {{{{h_{i}(t)}^{j\theta}} - {h_{i}( {t + 1} )}}}^{2}}}} & {{Equation}\mspace{14mu} 10}\end{matrix}$

Herein, in light of the maximum likelihood method, the mutual phaseelement θ_(ML) is equal to the value of θ, when the right side ofEquation 10 being differentiated with respect to θ is equal to 0. Theabove-described condition is shown in Equation 11 below:

$\begin{matrix}\begin{matrix}{{\frac{\;}{\theta}{\sum\limits_{i = 0}^{N - 1}\; {{{{h_{i}(t)}^{j\theta}} - {h_{i}( {t + 1} )}}}^{2}}} = {\frac{\;}{\theta}{\sum\limits_{i = 0}^{N - 1}\; ( {{{h_{i}(t)}^{j\theta}} - {h_{i}( {t + 1} )}} )}}} \\{( {{{h_{i}(t)}^{j\theta}} - {h_{i}( {t + 1} )}} )^{*}} \\{= {\frac{\;}{\theta}{\sum\limits_{i = 0}^{N - 1}\; \{ {{{h_{i}(t)}}^{2} + {{h_{i + 1}(t)}}^{2} -} }}} \\{{{{h_{i}(t)}{h_{i}^{*}( {t + 1} )}^{j\theta}} -}} \\ {{h_{i}^{*}(t)}{h_{i}( {t + 1} )}^{- {j\theta}}} \} \\{= {\sum\limits_{i = 0}^{N - 1}\; \{ {{j\; {h_{i}^{*}(t)}{h_{i}( {t + 1} )}^{- {j\theta}}} -} }} \\ {j\; {h_{i}^{*}(t)}{h_{i}( {t + 1} )}^{j\theta}} \} \\{= {j{\sum\limits_{i = 0}^{N - 1}\; {2{Im}\{ {{h_{i}^{*}(t)}{h_{i}( {t + 1} )}^{- {j\theta}}} \}}}}} \\{= 0}\end{matrix} & {{Equation}\mspace{14mu} 11}\end{matrix}$

The above Equation 11 may be simplified as shown in Equation 12 below:

$\begin{matrix}{{{{Im}\{ {^{- {j\theta}}{\sum\limits_{i = 0}^{N - 1}\; \{ {{h_{i}^{*}(t)}{h_{i}( {t + 1} )}} \}}} \}} = 0}{\theta_{ML} = {\arg( {\sum\limits_{i = 0}^{N - 1}\; {{h_{i}^{*}(t)}{h_{i}( {t + 1} )}}} )}}} & {{Equation}\mspace{14mu} 12}\end{matrix}$

More specifically, Equation 12 corresponds to the θ_(ML) value that isto be estimated by the argument of the correlation value betweenh_(i)(t) and h_(i)(t+1).

FIG. 52 illustrates a phase compensator according to an embodiment ofthe present invention, wherein the mutual phase element θ_(ML) iscalculated as described above, and wherein the estimated phase elementis compensated at the estimated CIR. Referring to FIG. 52, the phasecompensator includes a correlation calculator 3410, a phase changeestimator 3420, a compensation signal generator 3430, and a multiplier3440.

The correlation calculator 3410 includes a first N symbol buffer 3411,an N symbol delay 3412, a second N symbol buffer 3413, a conjugator3414, and a multiplier 3415. More specifically, the first N symbolbuffer 3411 included in the correlation calculator 3410 is capable ofstoring the data being inputted from the CIR estimator 3111 in symbolunits to a maximum limit of N number of symbols. The symbol data beingtemporarily stored in the first N symbol buffer 3411 are then inputtedto the multiplier 3415 included in the correlation calculator 3410 andto the multiplier 3440.

At the same time, the symbol data being outputted from the CIR estimator3111 are delayed by N symbols from the N symbol delay 3412. Then, thedelayed symbol data pass through the second N symbol buffer 3413 andinputted to the conjugator 3414, so as to be conjugated and theninputted to the multiplier 3415.

The multiplier 3415 multiplies the output of the first N symbol buffer3411 and the output of the conjugator 3414. Then, the multiplier 3415outputs the multiplied result to an accumulator 3421 included in thephase change estimator 3420.

More specifically, the correlation calculator 3410 calculates acorrelation between a current CIR h_(i)(t+1) having the length of N anda previous CIR h_(i)(t) also having the length of N. Then, thecorrelation calculator 3410 outputs the calculated correlation value tothe accumulator 3421 of the phase change estimator 3420.

The accumulator 3421 accumulates the correlation values outputted fromthe multiplier 3415 during an N symbol period. Then, the accumulator3421 outputs the accumulated value to the phase detector 3422. The phasedetector 3422 then calculates a mutual phase element θ_(ML) from theoutput of the accumulator 3421 as shown in the above-described Equation11. Thereafter, the calculated θ_(ML) value is outputted to thecompensation signal generator 3430.

The compensation signal generator 3430 outputs a complex signal e^(−jθ)^(ML) having a phase opposite to that of the detected phase as the phasecompensation signal to the multiplier 3440. The multiplier 3440multiplies the current CIR h_(i)(t+1) being outputted from the first Nsymbol buffer 3411 with the phase compensation signal e^(−jθ) ^(ML) ,thereby removing the amount of phase change of the estimated CIR.

The CIR having its phase change compensated, as described above, passesthrough a first cleaner (or pre-CIR cleaner) 3113 or bypasses the firstcleaner 3113, thereby being inputted to a CIR calculator (or CIRinterpolator-extrapolator) 3114. The CIR interpolator-extrapolator 3114either interpolates or extrapolates an estimated CIR, which is thenoutputted to a second cleaner (or post-CIR cleaner) 3115. Herein, theestimated CIR corresponds to a CIR having its phase change compensated.The first cleaner 3113 may or may not operate depending upon whether theCIR interpolator-extrapolator 3114 interpolates or extrapolates theestimated CIR. For example, if the CIR interpolator-extrapolator 3114interpolates the estimated CIR, the first cleaner 3113 does not operate.Conversely, if the CIR interpolator-extrapolator 3114 extrapolates theestimated CIR, the first cleaner 3113 operates.

More specifically, the CIR estimated from the known data includes achannel element that is to be obtained as well as a jitter elementcaused by noise. Since such jitter element deteriorates the performanceof the equalizer, it preferable that a coefficient calculator 3122removes the jitter element before using the estimated CIR. Therefore,according to the embodiment of the present invention, each of the firstand second cleaners 3113 and 3115 removes a portion of the estimated CIRhaving a power level lower than the predetermined threshold value (i.e.,so that the estimated CIR becomes equal to ‘0’). Herein, this removalprocess will be referred to as a “CIR cleaning” process.

The CIR interpolator-extrapolator 3114 performs CIR interpolation bymultiplying a CIR estimated from the CIR estimator 3112 by a coefficientand by multiplying a CIR having its phase change compensated from thephase compensator (or maximum likelihood phase compensator) 3112 byanother coefficient, thereby adding the multiplied values. At thispoint, some of the noise elements of the CIR may be added to oneanother, thereby being cancelled. Therefore, when the CIRinterpolator-extrapolator 3114 performs CIR interpolation, the original(or initial) CIR having noise elements remaining therein. In otherwords, when the CIR interpolator-extrapolator 3114 performs CIRinterpolation, an estimated CIR having its phase change compensated bythe phase compensator 3112 bypasses the first cleaner 3113 and isinputted to the CIR interpolator-extrapolator 3114. Subsequently, thesecond cleaner 3115 cleans the CIR interpolated by the CIRinterpolator-extrapolator 3114.

Conversely, the CIR interpolator-extrapolator 3114 performs CIRextrapolation by using a difference value between two CIRs, each havingits phase change compensated by the phase compensator 3112, so as toestimate a CIR positioned outside of the two CIRs. Therefore, in thiscase, the noise element is rather amplified. Accordingly, when the CIRinterpolator-extrapolator 3114 performs CIR extrapolation, the CIRcleaned by the first cleaner 3113 is used. More specifically, when theCIR interpolator-extrapolator 3114 performs CIR extrapolation, theextrapolated CIR passes through the second cleaner 3115, thereby beinginputted to the zero-padding unit 3116.

Meanwhile, when a second frequency domain converter (or fast fouriertransform (FFT2)) 3121 converts the CIR, which has been cleaned andoutputted from the second cleaner 3115, to a frequency domain, thelength and of the inputted CIR and the FFT size may not match (or beidentical to one another). In other words, the CIR length may be smallerthan the FFT size. In this case, the zero-padding unit 3116 adds anumber of zeros ‘0’s corresponding to the difference between the FFTsize and the CIR length to the inputted CIR, thereby outputting theprocessed CIR to the second frequency domain converter (FFT2) 3121.Herein, the zero-padded CIR may correspond to one of the interpolatedCIR, extrapolated CIR, and the CIR estimated in the known data section.

The second frequency domain converter 3121 performs FFT on the CIR beingoutputted from the zero padding unit 3116, thereby converting the CIR toa frequency domain CIR. Then, the second frequency domain converter 3121outputs the converted CIR to the coefficient calculator 3122.

The coefficient calculator 3122 uses the frequency domain CIR beingoutputted from the second frequency domain converter 3121 to calculatethe equalization coefficient. Then, the coefficient calculator 3122outputs the calculated coefficient to the distortion compensator 3130.Herein, for example, the coefficient calculator 3122 calculates achannel equalization coefficient of the frequency domain that canprovide minimum mean square error (MMSE) from the CIR of the frequencydomain, which is outputted to the distortion compensator 3130.

The distortion compensator 3130 performs a complex number multiplicationon the overlapped data of the frequency domain being outputted from theFFT unit 3102 of the first frequency domain converter 3100 and theequalization coefficient calculated by the coefficient calculator 3122,thereby compensating the channel distortion of the overlapped data beingoutputted from the FFT unit 3102.

FIG. 53 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 53illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 5.

More specifically, as shown in FIG. 5, known data that are sufficientlyare being periodically transmitted in regions A/B (i.e., MPH blocks B3to B8). Therefore, an indirect equalizing method using the CIR may beused herein. However, in regions C/D (i.e., MPH blocks B1, B2, B9, andB10), the known data are neither able to be transmitted at asufficiently long length nor able to be periodically and equallytransmitted. Therefore, it is inadequate to estimate the CIR by usingthe known data. Accordingly, in regions C/D, a direct equalizing methodin which an error is obtained from the output of the equalizer, so as toupdate the coefficient.

The examples presented in the embodiments of the present invention shownin FIG. 53 include a method of performing indirect channel equalizationby using a cyclic prefix on the data of regions A/B, and a method ofperforming direct channel equalization by using an overlap & save methodon the data of regions C/D.

Accordingly, referring to FIG. 53, the frequency domain channelequalizer includes a frequency domain converter 3510, a distortioncompensator 3520, a time domain converter 3530, a first coefficientcalculating unit 3540, a second coefficient calculating unit 3550, and acoefficient selector 3560.

Herein, the frequency domain converter 3510 includes an overlap unit3511, a select unit 3512, and a first FFT unit 3513.

The time domain converter 3530 includes an IFFT unit 3531, a save unit3532, and a select unit 3533.

The first coefficient calculating unit 3540 includes a CIR estimator3541, an average calculator 3542, and second FFT unit 3543, and acoefficient calculator 3544.

The second coefficient calculating unit 3550 includes a decision unit3551, a select unit 3552, a subtractor 3553, a zero-padding unit 3554, athird FFT unit 3555, a coefficient updater 3556, and a delay unit 3557.

Also, a multiplexer (MUX), which selects data that are currently beinginputted as the input data depending upon whether the data correspond toregions A/B or to regions C/D, may be used as the select unit 3512 ofthe frequency domain converter 3510, the select unit 3533 of the timedomain converter 3530, and the coefficient selector 3560.

In the channel equalizer having the above-described structure, as shownin FIG. 53, if the data being inputted correspond to the data of regionsA/B, the select unit 3512 of the frequency domain converter 3510 selectsthe input data and not the output data of the overlap unit 3511. In thesame case, the select unit 3533 of the time domain converter 3530selects the output data of the IFFT unit 3531 and not the output data ofthe save unit 3532. The coefficient selector 3560 selects theequalization coefficient being outputted from the first coefficientcalculating unit 3540.

Conversely, if the data being inputted correspond to the data of regionsC/D, the select unit 3512 of the frequency domain converter 3510 selectsthe output data of the overlap unit 3511 and not the input data. In thesame case, the select unit 3533 of the time domain converter 3530selects the output data of the save unit 3532 and not the output data ofthe IFFT unit 3531. The coefficient selector 3560 selects theequalization coefficient being outputted from the second coefficientcalculating unit 3550.

More specifically, the received data are inputted to the overlap unit3511 and select unit 3512 of the frequency domain converter 3510, and tothe first coefficient calculating unit 3540. If the inputted datacorrespond to the data of regions A/B, the select unit 3512 selects thereceived data, which are then outputted to the first FFT unit 3513. Onthe other hand, if the inputted data correspond to the data of regionsC/D, the select unit 3512 selects the data that are overlapped by theoverlap unit 3513 and are, then, outputted to the first FFT unit 3513.The first FFT unit 3513 performs FFT on the time domain data that areoutputted from the select unit 3512, thereby converting the time domaindata to frequency domain data. Then, the converted data are outputted tothe distortion compensator 3520 and the delay unit 3557 of the secondcoefficient calculating unit 3550.

The distortion compensator 3520 performs complex multiplication onfrequency domain data outputted from the first FFT unit 3513 and theequalization coefficient outputted from the coefficient selector 3560,thereby compensating the channel distortion detected in the data thatare being outputted from the first FFT unit 3513.

Thereafter, the distortion-compensated data are outputted to the IFFTunit 3531 of the time domain converter 3530. The IFFT unit 3531 of thetime domain converter 3530 performs IFFT on thechannel-distortion-compensated data, thereby converting the compensateddata to time domain data. The converted data are then outputted to thesave unit 3532 and the select unit 3533. If the inputted data correspondto the data of regions A/B, the select unit 3533 selects the output dataof the IFFT unit 3531. On the other hand, if the inputted datacorrespond to regions C/D, the select unit 3533 selects the valid dataextracted from the save unit 3532. Thereafter, the selected data areoutputted to be decoded and, simultaneously, outputted to the secondcoefficient calculating unit 3550.

The CIR estimator 3541 of the first coefficient calculating unit 3540uses the data being received during the known data section and the knowndata of the known data section, the known data being already known bythe receiving system in accordance with an agreement between thereceiving system and the transmitting system, in order to estimate theCIR. Subsequently, the estimated CIR is outputted to the averagecalculator 3542. The average calculator 3542 calculates an average valueof the CIRs that are being inputted consecutively. Then, the calculatedaverage value is outputted to the second FFT unit 3543. For example,referring to FIG. 37, the average value of the CIR value estimated atpoint T1 and the CIR value estimated at point T2 is used for the channelequalization process of the general data existing between point T1 andpoint T2. Accordingly, the calculated average value is outputted to thesecond FFT unit 3543.

The second FFT unit 3543 performs FFT on the CIR of the time domain thatis being inputted, so as to convert the inputted CIR to a frequencydomain CIR. Thereafter, the converted frequency domain CIR is outputtedto the coefficient calculator 3544. The coefficient calculator 3544calculates a frequency domain equalization coefficient that satisfiesthe condition of using the CIR of the frequency domain so as to minimizethe mean square error. The calculated equalizer coefficient of thefrequency domain is then outputted to the coefficient calculator 3560.

The decision unit 3551 of the second coefficient calculating unit 3550selects one of a plurality of decision values (e.g., 8 decision values)that is most approximate to the equalized data and outputs the selecteddecision value to the select unit 3552. Herein, a multiplexer may beused as the select unit 3552. In a general data section, the select unit3552 selects the decision value of the decision unit 3551.Alternatively, in a known data section, the select unit 3552 selects theknown data and outputs the selected known data to the subtractor 3553.The subtractor 3553 subtracts the output of the select unit 3533included in the time domain converter 3530 from the output of the selectunit 652 so as to calculate (or obtain) an error value. Thereafter, thecalculated error value is outputted to the zero-padding unit 3554.

The zero-padding unit 3554 adds (or inserts) the same amount of zeros(0) corresponding to the overlapped amount of the received data in theinputted error. Then, the error extended with zeros (0) is outputted tothe third FFT unit 3555. The third FFT unit 3555 converts the error ofthe time domain having zeros (0) added (or inserted) therein, to theerror of the frequency domain. Thereafter, the converted error isoutputted to the coefficient update unit 3556. The coefficient updateunit 3556 uses the received data of the frequency domain that have beendelayed by the delay unit 3557 and the error of the frequency domain soas to update the previous equalization coefficient. Thereafter, theupdated equalization coefficient is outputted to the coefficientselector 3560.

At this point, the updated equalization coefficient is stored so as thatit can be used as a previous equalization coefficient in a laterprocess. If the input data correspond to the data of regions A/B, thecoefficient selector 3560 selects the equalization coefficientcalculated from the first coefficient calculating unit 3540. On theother hand, if the input data correspond to the data of regions C/D, thecoefficient selector 3560 selects the equalization coefficient updatedby the second coefficient calculating unit 3550. Thereafter, theselected equalization coefficient is outputted to the distortioncompensator 3520.

FIG. 54 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 54illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 5. In this example, a method ofperforming indirect channel equalization by using an overlap & savemethod on the data of regions A/B, and a method of performing directchannel equalization by using an overlap & save method on the data ofregions C/D are illustrated.

Accordingly, referring to FIG. 54, the frequency domain channelequalizer includes a frequency domain converter 3610, a distortioncompensator 3620, a time domain converter 3630, a first coefficientcalculating unit 3640, a second coefficient calculating unit 3650, and acoefficient selector 3660.

Herein, the frequency domain converter 3610 includes an overlap unit3611 and a first FFT unit 3612.

The time domain converter 3630 includes an IFFT unit 3631 and a saveunit 3632.

The first coefficient calculating unit 3640 includes a CIR estimator3641, an interpolator 3642, a second FFT unit 3643, and a coefficientcalculator 3644.

The second coefficient calculating unit 3650 includes a decision unit3651, a select unit 3652, a subtractor 3653, a zero-padding unit 3654, athird FFT unit 3655, a coefficient updater 3656, and a delay unit 3657.

Also, a multiplexer (MUX), which selects data that are currently beinginputted as the input data depending upon whether the data correspond toregions A/B or to regions C/D, may be used as the coefficient selector3660. More specifically, if the input data correspond to the data ofregions A/B, the coefficient selector 3660 selects the equalizationcoefficient calculated from the first coefficient calculating unit 3640.On the other hand, if the input data correspond to the data of regionsC/D, the coefficient selector 3660 selects the equalization coefficientupdated by the second coefficient calculating unit 3650.

In the channel equalizer having the above-described structure, as shownin FIG. 54, the received data are inputted to the overlap unit 3611 ofthe frequency domain converter 3610 and to the first coefficientcalculating unit 3640. The overlap unit 3611 overlaps the input data toa pre-determined overlapping ratio and outputs the overlapped data tothe first FFT unit 3612. The first FFT unit 3612 performs FFT on theoverlapped time domain data, thereby converting the overlapped timedomain data to overlapped frequency domain data. Then, the converteddata are outputted to the distortion compensator 3620 and the delay unit3657 of the second coefficient calculating unit 3650.

The distortion compensator 3620 performs complex multiplication on theoverlapped frequency domain data outputted from the first FFT unit 3612and the equalization coefficient outputted from the coefficient selector3660, thereby compensating the channel distortion detected in theoverlapped data that are being outputted from the first FFT unit 3612.Thereafter, the distortion-compensated data are outputted to the IFFTunit 3631 of the time domain converter 3630. The IFFT unit 3631 of thetime domain converter 3630 performs IFFT on the distortion-compensateddata, thereby converting the compensated data to overlapped time domaindata. The converted overlapped data are then outputted to the save unit3632. The save unit 3632 extracts only the valid data from theoverlapped time domain data, which are then outputted for data decodingand, at the same time, outputted to the second coefficient calculatingunit 3650 in order to update the coefficient.

The CIR estimator 3641 of the first coefficient calculating unit 3640uses the data received during the known data section and the known datain order to estimate the CIR. Subsequently, the estimated CIR isoutputted to the interpolator 3642. The interpolator 3642 uses theinputted CIR to estimate the CIRs (i.e., CIRs of the region that doesnot include the known data) corresponding to the points located betweenthe estimated CIRs according to a predetermined interpolation method.Thereafter, the estimated result is outputted to the second FFT unit3643. The second FFT unit 3643 performs FFT on the inputted CIR, so asto convert the inputted CIR to a frequency domain CIR. Thereafter, theconverted frequency domain CIR is outputted to the coefficientcalculator 3644. The coefficient calculator 3644 calculates a frequencydomain equalization coefficient that satisfies the condition of usingthe CIR of the frequency domain so as to minimize the mean square error.The calculated equalizer coefficient of the frequency domain is thenoutputted to the coefficient calculator 3660.

The structure and operations of the second coefficient calculating unit3650 is identical to those of the second coefficient calculating unit3550 shown in FIG. 53. Therefore, the description of the same will beomitted for simplicity.

If the input data correspond to the data of regions A/B, the coefficientselector 3660 selects the equalization coefficient calculated from thefirst coefficient calculating unit 3640. On the other hand, if the inputdata correspond to the data of regions C/D, the coefficient selector3660 selects the equalization coefficient updated by the secondcoefficient calculating unit 3650. Thereafter, the selected equalizationcoefficient is outputted to the distortion compensator 3620.

FIG. 55 illustrates a block diagram of a channel equalizer according toanother embodiment of the present invention. In other words, FIG. 55illustrates a block diagram showing another example of a channelequalizer by using different CIR estimation and application methods inaccordance with regions A, B, C, and D, when the data group is dividedinto the structure shown in FIG. 5. For example, in regions A/B, thepresent invention uses the known data in order to estimate the CIR byusing a least square (LS) method, thereby performing the channelequalization process. On the other hand, in regions C/D, the presentinvention estimates the CIR by using a least mean square (LMS) method,thereby performing the channel equalization process. More specifically,since the periodic known data do not exist in regions C/D, as in regionsA/B, the same channel equalization process as that of regions A/B cannotbe performed in regions C/D. Therefore, the channel equalization processmay only be performed by using the LMS method.

Referring to FIG. 55, the channel equalizer includes an overlap unit3701, a first fast fourier transform (FFT) unit 3702, a distortioncompensator 3703, an inverse fast fourier transform (IFFT) unit 3704, asave unit 3705, a first CIR estimator 3706, a CIR interpolator 3707, adecision unit 3708, a second CIR estimator 3710, a selection unit 3711,a second FFT unit 3712, and a coefficient calculator 3713. Herein, anydevice performed complex number multiplication may be used as thedistortion compensator 3703. In the channel equalizer having theabove-described structure, as shown in FIG. 55, the overlap unit 3701overlaps the data being inputted to the channel equalizer to apredetermined overlapping ratio and then outputs the overlapped data tothe first FFT unit 3702. The first FFT unit 3702 converts (ortransforms) the overlapped data of the time domain to overlapped data ofthe frequency domain by using fast fourier transform (FFT). Then, theconverted data are outputted to the distortion compensator 3703.

The distortion converter 3703 performs complex multiplication on theequalization coefficient calculated from the coefficient calculator 3713and the overlapped data of the frequency domain, thereby compensatingthe channel distortion of the overlapped data being outputted from thefirst FFT unit 3702. Thereafter, the distortion-compensated data areoutputted to the IFFT unit 3704. The IFFT unit 3704 performs inversefast fourier transform (IFFT) on the distortion-compensated overlappeddata, so as to convert the corresponding data back to data (i.e.,overlapped data) of the time domain. Subsequently, the converted dataare outputted to the save unit 3705. The save unit 3705 extracts onlythe valid data from the overlapped data of the time domain. Then, thesave unit 3705 outputs the extracted valid data for a data decodingprocess and, at the same time, outputs the extracted valid data to thedecision unit 3708 for a channel estimation process.

The decision unit 3708 selects one of a plurality of decision values(e.g., 8 decision values) that is most approximate to the equalized dataand outputs the selected decision value to the select unit 3709. Herein,a multiplexer may be used as the select unit 3709. In a general datasection, the select unit 3709 selects the decision value of the decisionunit 3708. Alternatively, in a known data section, the select unit 3709selects the known data and outputs the selected known data to the secondCIR estimator 3710.

Meanwhile, the first CIR estimator 3706 uses the data that are beinginputted in the known data section and the known data so as to estimatethe CIR.

Thereafter, the first CIR estimator 3706 outputs the estimated CIR tothe CIR interpolator 3707. Herein, the known data correspond toreference known data created during the known data section by thereceiving system in accordance to an agreement between the transmittingsystem and the receiving system. At this point, according to anembodiment of the present invention, the first CIR estimator 3706 usesthe LS method to estimate the CIR. The LS estimation method calculates across correlation value p between the known data that have passedthrough the channel during the known data section and the known datathat are already known by the receiving end. Then, a cross correlationmatrix R of the known data is calculated. Subsequently, a matrixoperation is performed on R⁻¹·p so that the cross correlation portionwithin the cross correlation value p between the received data and theinitial known data, thereby estimating the CIR of the transmissionchannel.

The CIR interpolator 3707 receives the CIR from the first CIR estimator3706. And, in the section between two sets of known data, the CIR isinterpolated in accordance with a pre-determined interpolation method.Then, the interpolated CIR is outputted. At this point, thepre-determined interpolation method corresponds to a method ofestimating a particular set of data at an unknown point by using a setof data known by a particular function. For example, such methodincludes a linear interpolation method. The linear interpolation methodis only one of the most simple interpolation methods. A variety of otherinterpolation methods may be used instead of the above-described linearinterpolation method. It is apparent that the present invention is notlimited only to the example set forth in the description of the presentinvention. More specifically, the CIR interpolator 3707 uses the CIRthat is being inputted in order to estimate the CIR of the section thatdoes not include any known data by using the pre-determinedinterpolation method. Thereafter, the estimated CIR is outputted to theselect unit 3711.

The second CIR estimator 3710 uses the input data of the channelequalizer and the output data of the select unit 3709 in order toestimate the CIR. Then, the second CIR estimator 3710 outputs theestimated CIR to the select unit 3711. At this point, according to anembodiment of the present invention, the CIR is estimated by using theLMS method. The LMS estimation method will be described in detail in alater process.

In regions A/B (i.e., MPH blocks B3 to B8), the select unit 3711 selectsthe CIR outputted from the CIR interpolator 3707. And, in regions C/D(i.e., MPH blocks B1, B2, B9, and B10), the select unit 3711 selects theCIR outputted from the second CIR estimator 3710. Thereafter, the selectunit 3711 outputs the selected CIR to the second FFT unit 3712.

The second FFT unit 3712 converts the CIR that is being inputted to aCIR of the frequency domain, which is then outputted to the coefficientcalculator 3713. The coefficient calculator 3713 uses the CIR of thefrequency domain that is being inputted, so as to calculate theequalization coefficient and to output the calculated equalizationcoefficient to the distortion compensator 3703. At this point, thecoefficient calculator 3713 calculates a channel equalizationcoefficient of the frequency domain that can provide minimum mean squareerror (MMSE) from the CIR of the frequency domain. At this point, thesecond CIR estimator 3710 may use the CIR estimated in regions A/B asthe CIR at the beginning of regions C/D. For example, the CIR value ofMPH block B8 may be used as the CIR value at the beginning of the MPHblock B9. Accordingly, the convergence speed of regions C/D may bereduced.

The basic principle of estimating the CIR by using the LMS method in thesecond CIR estimator 3710 corresponds to receiving the output of anunknown transmission channel and to updating (or renewing) thecoefficient of an adaptive filter (not shown) so that the differencevalue between the output value of the unknown channel and the outputvalue of the adaptive filter is minimized. More specifically, thecoefficient value of the adaptive filter is renewed so that the inputdata of the channel equalizer is equal to the output value of theadaptive filter (not shown) included in the second CIR estimator 3710.Thereafter, the filter coefficient is outputted as the CIR after eachFFT cycle.

Referring to FIG. 56, the second CIR estimator 3710 includes a delayunit T, a multiplier, and a coefficient renewal unit for each tab.Herein, the delay unit T sequentially delays the output data {circumflexover (x)}(n) of the select unit 3709. The multiplier multipliesrespective output data outputted from each delay unit T with error datae(n). The coefficient renewal unit renews the coefficient by using theoutput corresponding to each multiplier. Herein, the multipliers thatare being provided as many as the number of tabs will be referred to asa first multiplying unit for simplicity. Furthermore, the second CIRestimator 3710 further includes a plurality of multipliers eachmultiplying the output data of the select unit 3709 and the output dataof the delay unit T (wherein the output data of the last delay unit areexcluded) with the output data corresponding to each respectivecoefficient renewal unit. These multipliers are also provided as many asthe number of tabs. This group of multipliers will be referred to as asecond multiplying unit for simplicity.

The second CIR estimator 3710 further includes an adder and asubtractor. Herein, the adder adds all of the data outputted from eachmultipliers included in the second multiplier unit. Then, the addedvalue is outputted as the estimation value ŷ(n) of the data inputted tothe channel equalizer. The subtractor calculates the difference betweenthe output data ŷ(n) of the adder and the input data y(n) of the channelequalizer. Thereafter, the calculated difference value is outputted asthe error data e(n). Referring to FIG. 56, in a general data section,the decision value of the equalized data is inputted to the first delayunit included in the second CIR estimator 3710 and to the firstmultiplier included in the second multiplier. In the known data section,the known data are inputted to the first delay unit included in thesecond CIR estimator 3710 and to the first multiplier included in thesecond multiplier unit. The input data {circumflex over (x)}(n) aresequentially delayed by passing through a number of serially connecteddelay units T, the number corresponding to the number of tabs. Theoutput data of each delay unit T and the error data e(n) are multipliedby each corresponding multiplier included in the first multiplier unit.Thereafter, the coefficients are renewed by each respective coefficientrenewal unit.

Each coefficient that is renewed by the corresponding coefficientrenewal unit is multiplied with the input data the output data{circumflex over (x)}(n) and also with the output data of each delayunit T with the exception of the last delay. Thereafter, the multipliedvalue is inputted to the adder. The adder then adds all of the outputdata outputted from the second multiplier unit and outputs the addedvalue to the subtractor as the estimation value ŷ(n) of the input dataof the channel equalizer. The subtractor calculates a difference valuebetween the estimation value ŷ(n) and the input data y(n) of the channelequalizer. The difference value is then outputted to each multiplier ofthe first multiplier unit as the error data e(n). At this point, theerror data e(n) is outputted to each multiplier of the first multiplierunit by passing through each respective delay unit T. As describedabove, the coefficient of the adaptive filter is continuously renewed.And, the output of each coefficient renewal unit is outputted as the CIRof the second CIR estimator 3710 after each FFT cycle.

Block Decoder

Meanwhile, if the data being inputted to the block decoder 1005, afterbeing channel-equalized by the equalizer 1003, correspond to the datahaving both block encoding and trellis encoding performed thereon (i.e.,the data within the RS frame, the signaling information data, etc.) bythe transmitting system, trellis decoding and block decoding processesare performed on the inputted data as inverse processes of thetransmitting system. Alternatively, if the data being inputted to theblock decoder 1005 correspond to the data having only trellis encodingperformed thereon (i.e., the main service data), and not the blockencoding, only the trellis decoding process is performed on the inputteddata as the inverse process of the transmitting system.

The trellis decoded and block decoded data by the block decoder 1005 arethen outputted to the RS frame decoder 1006. More specifically, theblock decoder 1005 removes the known data, data used for trellisinitialization, and signaling information data, MPEG header, which havebeen inserted in the data group, and the RS parity data, which have beenadded by the RS encoder/non-systematic RS encoder or non-systematic RSencoder of the transmitting system. Then, the block decoder 1005 outputsthe processed data to the RS frame decoder 1006. Herein, the removal ofthe data may be performed before the block decoding process, or may beperformed during or after the block decoding process.

Meanwhile, the data trellis-decoded by the block decoder 1005 areoutputted to the data deinterleaver 1009. At this point, the data beingtrellis-decoded by the block decoder 1005 and outputted to the datadeinterleaver 1009 may not only include the main service data but mayalso include the data within the RS frame and the signaling information.Furthermore, the RS parity data that are added by the transmittingsystem after the pre-processor 230 may also be included in the databeing outputted to the data deinterleaver 1009.

According to another embodiment of the present invention, data that arenot processed with block decoding and only processed with trellisencoding by the transmitting system may directly bypass the blockdecoder 1005 so as to be outputted to the data deinterleaver 1009. Inthis case, a trellis decoder should be provided before the datadeinterleaver 1009. More specifically, if the inputted data correspondto the data having only trellis encoding performed thereon and not blockencoding, the block decoder 1005 performs Viterbi (or trellis) decodingon the inputted data so as to output a hard decision value or to performa hard-decision on a soft decision value, thereby outputting the result.

Meanwhile, if the inputted data correspond to the data having both blockencoding process and trellis encoding process performed thereon, theblock decoder 1005 outputs a soft decision value with respect to theinputted data.

In other words, if the inputted data correspond to data being processedwith block encoding by the block processor 302 and being processed withtrellis encoding by the trellis encoding module 256, in the transmittingsystem, the block decoder 1005 performs a decoding process and a trellisdecoding process on the inputted data as inverse processes of thetransmitting system. At this point, the RS frame encoder of thepre-processor included in the transmitting system may be viewed as anouter (or external) encoder. And, the trellis encoder may be viewed asan inner (or internal) encoder. When decoding such concatenated codes,in order to allow the block decoder 1005 to maximize its performance ofdecoding externally encoded data, the decoder of the internal codeshould output a soft decision value.

FIG. 57 illustrates a detailed block view of the block decoder 1005according to an embodiment of the present invention. Referring to FIG.57, the block decoder 1005 includes a feedback controller 4010, an inputbuffer 4011, a trellis decoding unit (or 12-way trellis coded modulation(TCM) decoder or inner decoder) 4012, a symbol-byte converter 4013, anouter block extractor 4014, a feedback deformatter 4015, a symboldeinterleaver 4016, an outer symbol mapper 4017, a symbol decoder 4018,an inner symbol mapper 4019, a symbol interleaver 4020, a feedbackformatter 4021, and an output buffer 4022. Herein, just as in thetransmitting system, the trellis decoding unit 4012 may be viewed as aninner (or internal) decoder. And, the symbol decoder 4018 may be viewedas an outer (or external) decoder.

The input buffer 4011 temporarily stores the mobile service data symbolsbeing channel-equalized and outputted from the equalizer 1003. (Herein,the mobile service data symbols may include symbols corresponding to thesignaling information, RS parity data symbols and CRC data symbols addedduring the encoding process of the RS frame.) Thereafter, the inputbuffer 4011 repeatedly outputs the stored symbols for M number of timesto the trellis decoding unit 4012 in a turbo block (TEL) size requiredfor the turbo decoding process. Herein, the size of the input buffer4011 is larger than or equal to the size of the turbo block (TBL)required for turbo decoding. The turbo block (TBL) size is larger thanor equal to the block length (BK) of the symbol interleaver within theblock processor. More specifically, there are no limitations for inputdata configured only of symbols that are not processed with blockencoding, since such input data bypass the inputted buffer 4011.

Conversely, the input data including symbols processed with blockencoding are stored in the input buffer 4011. At this point, the inputdata should include a number of symbols being inputted to the symbolinterleaver, wherein the number of symbols is equivalent to the blocklength (K). Therefore, in this case, the length of the TBL is largerthan or equal to BK. Also, M represents a number of repetitions of theturbo decoding process, the number being predetermined by the feedbackcontroller 4010. More specifically, the input buffer 4011 stores mobileservice data symbols corresponding to the block size TBL for the blockdecoding process. Herein, the mobile service data symbols correspondingto the block size TBL required for the block decoding process arerepeatedly outputted to the trellis decoding unit 4012 as many times asthe number of cycle periods during the turbo decoding process.

Furthermore, if a symbol being channel-equalized and outputted from theequalizer 1003 does not correspond to a mobile service data symbol(wherein the mobile service data symbol includes symbols correspondingto the signaling information, RS parity data symbols that are addedduring the encoding process of the RS frame, and CRC data symbols), theinput buffer 4011 does not store nor repeatedly output the correspondingsymbol and directly outputs the symbol to the trellis decoding unit 4012without modification. Herein, the storage, repetition, and output of theinput buffer 4011 are controlled by the feedback controller 4010.

The trellis decoding unit 4012 includes a 12-way trellis encoder, shownin FIG. 22, and a 12-way TCM decoder. Herein, the trellis decoding unit4012 performs 12-way trellis decoding as inverse processes of the 12-waytrellis encoder. More specifically, the trellis decoding unit 4012receives a number of output symbols of the input buffer 4011 andsoft-decision values of the feedback formatter 4021 equivalent to eachTBL, so as to perform the TCM decoding process. At this point, basedupon the control of the feedback controller 4010, the soft-decisionvalues outputted from the feedback formatter 4021 are matched with anumber of mobile service data symbol places so as to be in a one-to-one(1:1) correspondence. Herein, the number of mobile service data symbolplaces is equivalent to the TBL being outputted from the input buffer4011.

More specifically, the mobile service data being outputted from theinput buffer 4011 are matched with the turbo decoded data beinginputted, so that each respective data place can correspond with oneanother. Thereafter, the matched data are outputted to the trellisdecoding unit 4012. For example, if the turbo decoded data correspond tothe third symbol within the turbo block, the corresponding symbol (ordata) is matched with the third symbol included in the turbo block,which is outputted from the input buffer 4011. Subsequently, the matchedsymbol (or data) is outputted to the trellis decoding unit 4012.

In order to do so, while the regressive turbo decoding is in process,the feedback controller 4010 controls the input buffer 4011 so that theinput buffer 4011 stores the corresponding turbo block data. Also, bydelaying data (or symbols), the soft decision value (e.g., LLR) of thesymbol outputted from the symbol interleaver 4020 and the symbol of theinput buffer 4011 corresponding to the same place (or position) withinthe block of the output symbol are matched with one another to be in aone-to-one correspondence. Thereafter, the matched symbols arecontrolled so that they can be inputted to the TCM decoder through therespective path. This process is repeated for a predetermined number ofturbo decoding cycle periods. Then, the data of the next turbo block areoutputted from the input buffer 4011, thereby repeating the turbodecoding process.

The output of the trellis decoding unit 4012 signifies a degree ofreliability of the transmission bits configuring each symbol. Forexample, in the transmitting system, since the input data of the trellisencoding module correspond to two bits as one symbol, a log likelihoodratio (LLR) between the likelihood of a bit having the value of ‘1’ andthe likelihood of the bit having the value of ‘0’ may be respectivelyoutputted (in bit units) to the upper bit and the lower bit. Herein, thelog likelihood ratio corresponds to a log value for the ratio betweenthe likelihood of a bit having the value of ‘1’ and the likelihood ofthe bit having the value of ‘0’. Alternatively, a LLR for the likelihoodof 2 bits (i.e., one symbol) being equal to “00”, “01”, “10”, and “11”may be respectively outputted (in symbol units) to all 4 combinations ofbits (i.e., 00, 01, 10, 11). Consequently, this becomes the softdecision value that indicates the degree of reliability of thetransmission bits configuring each symbol. A maximum a posterioriprobability (MAP) or a soft-out Viterbi algorithm (SOVA) may be used asa decoding algorithm of each TCM decoder within the trellis decodingunit 4012.

The output of the trellis decoding unit 4012 is inputted to thesymbol-byte converter 4013 and the outer block extractor 4014. Thesymbol-byte converter 4013 performs a hard-decision process of the softdecision value that is trellis decoded and outputted from the trellisdecoding unit 4012. Thereafter, the symbol-byte converter 4013 groups 4symbols into byte units, which are then outputted to the datadeinterleaver 1009. More specifically, the symbol-byte converter 4013performs hard-decision in bit units on the soft decision value of thesymbol outputted from the trellis decoding unit 4012. Therefore, thedata processed with hard-decision and outputted in bit units from thesymbol-byte converter 4013 not only include main service data, but mayalso include mobile service data, known data, RS parity data, and MPEGheaders.

Among the soft decision values of the trellis decoding unit 4012, theouter block extractor 4014 identifies the soft decision valuescorresponding to the mobile service data symbols (wherein symbolscorresponding to signaling information, RS parity data symbols that areadded during the encoding of the RS frame, and CRC data symbols areincluded) and outputs the identified soft decision values to thefeedback deformatter 4015. The feedback deformatter 4015 changes theprocessing order of the soft decision values corresponding to the mobileservice data symbols. This is an inverse process of an initial change inthe processing order of the mobile service data symbols, which aregenerated during an intermediate step, wherein the output symbolsoutputted from the block processor 303 of the transmitting system arebeing inputted to the trellis encoding module (e.g., when the symbolspass through the group formatter, the data deinterleaver, the packetformatter, the RS encoder, and the data interleaver). Thereafter, thefeedback deformatter 4015 outputs the processed mobile service datasymbols to the symbol deinterleaver 4016.

The symbol deinterleaver 4016 performs deinterleaving on the mobileservice data symbols having their processing orders changed andoutputted from the feedback deformatter 4015, as an inverse process ofthe symbol interleaving process of the symbol interleaver 403 includedin the transmitting system. The size of the block used by the symboldeinterleaver 4016 during the deinterleaving process is identical tointerleaving size of an actual symbol (i.e., BK) of the symbolinterleaver, shown in FIG. 19, which is included in the transmittingsystem. This is because the turbo decoding process is performed betweenthe trellis decoding unit 4012 and the symbol decoder 4018. Both theinput and output of the symbol deinterleaver 4016 correspond to softdecision values, and the deinterleaved soft decision values areoutputted to the outer symbol mapper 4017.

The operations of the outer symbol mapper 4017 may vary depending uponthe structure and coding rate of the symbol encoder 402 included in thetransmitting system. For example, when data are ½-rate encoded by thesymbol encoder 402 and then transmitted, the outer symbol mapper 4017directly outputs the input data without modification. In anotherexample, when data are ¼-rate encoded by the symbol encoder 402 and thentransmitted, the outer symbol mapper 4017 converts the input data sothat it can match the input data format of the symbol decoder 4018.Then, the outer symbol mapper 4017 outputs the converted data to thesymbol decoder 4018.

The symbol decoder 4018 (i.e., the outer decoder) receives the dataoutputted from the outer symbol mapper 4017 and performs symbol decodingas an inverse process of the symbol encoder 402 included in thetransmitting system. At this point, two different soft decision valuesare outputted from the symbol decoder 4018. One of the outputted softdecision values corresponds to a soft decision value matching the outputsymbol of the symbol encoder 402 (hereinafter referred to as a “firstdecision value”). The other one of the outputted soft decision valuescorresponds to a soft decision value matching the input bit of thesymbol encoder 402 (hereinafter referred to as a “second decisionvalue”).

More specifically, the first decision value represents a degree ofreliability the output symbol (i.e., 2 bits) of the symbol encoder 402.Herein, the first soft decision value may output (in bit units) a LLRbetween the likelihood of 1 bit being equal to ‘1’ and the likelihood of1 bit being equal to ‘0’ with respect to each of the upper bit and lowerbit, which configures a symbol. Alternatively, the first soft decisionvalue may also output (in symbol units) a LLR for the likelihood of 2bits being equal to “00”, “01”, “10”, and “11” with respect to allpossible combinations. The first soft decision value is fed-back to thetrellis decoding unit 4012 through the inner symbol mapper 4019, thesymbol interleaver 4020, and the feedback formatter 4021. On the otherhand, the second soft decision value indicates a degree of reliabilitythe input bit of the symbol encoder 402 included in the transmittingsystem. Herein, the second soft decision value is represented as the LLRbetween the likelihood of 1 bit being equal to ‘1’ and the likelihood of1 bit being equal to ‘0’. Thereafter, the second soft decision value isoutputted to the outer buffer 4022. In this case, a maximum a posterioriprobability (MAP) or a soft-out Viterbi algorithm (SOVA) may be used asthe decoding algorithm of the symbol decoder 4018.

The first soft decision value that is outputted from the symbol decoder4018 is inputted to the inner symbol mapper 4019. The inner symbolmapper 4019 converts the first soft decision value to a data formatcorresponding the input data of the trellis decoding unit 4012.Thereafter, the inner symbol mapper 4019 outputs the converted softdecision value to the symbol interleaver 4020. The operations of theinner symbol mapper 4019 may also vary depending upon the structure andcoding rate of the symbol encoder 402 included in the transmittingsystem.

Hereinafter, when the symbol encoder 402 of the transmitting systemoperates as a ¼ encoder, the operations of the outer symbol mapper 4017and the inner symbol mapper 4019 will now be described in detail withreference to FIG. 17A to FIG. 17C. According to an embodiment of thepresent invention, it is assumed that the symbol encoder is configuredas shown in FIG. 17A, and that the ¼ outer encoder 411 encodes one bit Uso as to output 4 bits u0, u1, u2, and u3, and also that the 4 bits(i.e., 2 symbols) are transmitted twice in symbol units (i.e., each ofthe 2 symbols is transmitted twice) through the parallel/serialconverter 412. In this case, the symbol that is outputted first isreferred to as an odd-number-designated symbol, and the symbol that isoutputted subsequently is referred to as an even-number-designatedsymbol for simplicity.

At this point, when the input/output units of the outer symbol mapper4017 and the inner symbol mapper 4019 corresponds to symbol units, 16(i.e., 2⁴=16) different soft decision values may be outputted in symbolunits from the outer symbol mapper 4017. For example, among the 16(i.e., 2⁴=16) different soft decision values that are to be outputtedfrom the outer symbol mapper 4017, the soft decision value of s=(1, 0,0, 1) may be calculated by adding the soft decision value of theinputted odd-number-designated symbol m₀=(1, 0) and the soft decisionvalue of the inputted even-number-designated symbol m₂=(0, 1).Afterwards, the added value is inputted to the symbol decoder 4018.

Furthermore, a total of 4 (i.e., 2²=4) different soft decision valuesmay be outputted in symbol units from the inner symbol mapper 4019. Forexample, among the 4 (i.e., 2²=4) different soft decision values thatare to be outputted from the inner symbol mapper 4019, the soft decisionvalue of the odd-number-designated symbol m₀=(1, 1) may be obtained bycalculating the largest value among the soft decision value for each ofthe output symbols s=(1, 1, X, X) outputted from the symbol decoder4018. Afterwards, the added value is inputted to the symbol decoder4018. Also, the soft decision value of the even-number-designated symbolm₁=(0, 0) may be obtained by calculating the largest value among thesoft decision value for each of the output symbols s=(X, X, 0, 0)outputted from the symbol decoder 4018. Herein, ‘X’ randomly correspondsto one of ‘1’ and ‘0’. The output of the inner symbol mapper 4019 isthen provided to the symbol interleaver 4020.

Meanwhile, if the input/output units of the outer symbol mapper 4017 andthe inner symbol mapper 4019 correspond to bit units, a total of 4different soft decision values may be outputted in bit units from theouter symbol mapper 4017. More specifically, the outer symbol mapper4017 simultaneously outputs 2 soft decision values of anodd-number-designated input symbol (i.e., a soft decision value for eachof the upper bit and lower bit configuring the odd-number-designatedinput symbol) and 2 soft decision values of an even-number-designatedinput symbol (i.e., a soft decision value for each of the upper bit andlower bit configuring the even-number-designated input symbol) to thesymbol decoder 4018. Also, with respect to the 4 inputs provided by thesymbol decoder 4018, the inner symbol mapper 4019 also identifies 2 softdecision values of an odd-number-designated output symbol (i.e., a softdecision value for each of the upper bit and lower bit configuring theodd-number-designated output symbol of the symbol decoder 4018) and 2soft decision values of an even-number-designated output symbol (i.e., asoft decision value for each of the upper bit and lower bit configuringthe even-number-designated output symbol of the symbol decoder 4018),which are then outputted to the symbol interleaver 4020.

In other words, if the symbol encoding process is performed as shown inFIG. 17A, the LLR for each of the 16 symbols is respectively receivedand symbol-decoded. Thereafter, the processed LLR for each of the 16symbols may be outputted as the first soft decision value.Alternatively, the LLR for each of the 4 symbols is respectivelyreceived and symbol-decoded. Thereafter, the processed LLR for each ofthe 4 symbols may be outputted as the first soft decision value.

According to another embodiment of the present invention, it is assumedthat the symbol encoder is configured as shown in FIG. 17B, and that the½ outer encoder 421 encodes one bit U so as to output 2 bits u0 and u1,and also that the 2 bits (i.e., 1 symbol) is repeated once through therepeater 422. In this case, the symbol that is outputted first isreferred to as an odd-number-designated symbol, and the symbol that isoutputted subsequently is referred to as an even-number-designatedsymbol for simplicity.

At this point, when the input/output units of the outer symbol mapper4017 and the inner symbol mapper 4019 corresponds to symbol units, 4(i.e., 2²=4) different soft decision values may be outputted in symbolunits from the outer symbol mapper 4017. For example, among the 4 (i.e.,2²=4) different soft decision values that are to be outputted in symbolunits from the outer symbol mapper 4017, the soft decision value ofs=(1, 0) may be calculated by adding the soft decision value of theinputted odd-number-designated symbol m₀=(1, 0) and the soft decisionvalue of the inputted even-number-designated symbol m₁=(1, 0).Afterwards, the added value is provided to the symbol decoder 4018.Furthermore, a total of 4 (i.e., 2²=4) different soft decision values isto be outputted from the inner symbol mapper 4019. For example, amongthe 4 (i.e., 2²=4) different soft decision values, the soft decisionvalue of the odd-number-designated symbol m₀=(1, 1) and theeven-number-designated symbol m₁=(1, 1) become the soft decision valueof the input symbol s=(1, 1) of the symbol decoder 4018. This softdecision value is then outputted to the symbol interleaver 4020.

Meanwhile, if the input/output units of the outer symbol mapper 4017 andthe inner symbol mapper 4019 correspond to bit units, a total of 2 softdecision values (i.e., a soft decision for the upper bit and a softdecision value for the lower bit) may be outputted in bit units from theouter symbol mapper 4017. Herein, the soft decision value for the upperbit may be obtained by adding the soft decision for the upper bit of theodd-number-designated symbol and the soft decision for the upper bit ofthe even-number-designated symbol. Also, the soft decision value for thelower bit may be obtained by adding the soft decision for the lower bitof the odd-number-designated symbol and the soft decision for the lowerbit of the even-number-designated symbol.

The inner symbol mapper 4019 receives the soft decision value for theupper bit and the soft decision value for the lower bit from the symboldecoder 4018. Thereafter, the inner symbol mapper 4019 outputs thereceived soft decision values as 2 soft decision values corresponding toeach of the odd-number-designated output bits (i.e., a soft decisionvalue for each of the lower bit and upper bit that are outputted fromthe symbol decoder 4018). Then, the 2 soft decision values correspondingto each of the odd-number-designated output bits are repeated, therebybeing outputted as 2 soft decision values corresponding to each of theeven-number-designated output bits.

According to yet another embodiment of the present invention, it isassumed that the symbol encoder is configured as shown in FIG. 17C, andthat the input bit is repeated once by the repeater 431, and that the ½outer encoder 432 ½-rate encodes the bit that is repeated and inputtedfrom the repeater 431, so as to output 2 bits u0 and u1 (i.e., 1 symbol)twice. In this case, the symbol encoder repeats one bit and encodes therepeated bit at a coding rate of ½. Herein, the symbol that is outputtedfirst is referred to as an odd-number-designated symbol, and the symbolthat is outputted subsequently is referred to as aneven-number-designated symbol for simplicity.

At this point, if the input/output units of the outer symbol mapper 4017and the inner symbol mapper 4019 correspond to bit units, the outersymbol mapper 4017 directly transmits the output of the symboldeinterleaver 4016 to the symbol decoder 4018 without modification. Theinner symbol mapper 4019 directly transmits the output of the symboldecoder 4018 to the symbol interleaver 4020 without modification. Also,even when the input/output units of the outer symbol mapper 4017 and theinner symbol mapper 4019 correspond to symbol units, the outer symbolmapper 4017 directly transmits the output of the symbol deinterleaver4016 to the symbol decoder 4018 without modification. The inner symbolmapper 4019 directly transmits the output of the symbol decoder 4018 tothe symbol interleaver 4020 without modification.

Referring to FIG. 17C, since the input of the ½ outer encoder 432 isrepeated by the repeater 431, the soft decisions values for the 2symbols corresponding to the output data of the block decoder should bedetermined and outputted as a single soft decision value. Morespecifically, when the symbol encoding is processed as shown in FIG. 17Band FIG. 17C, the LLR for each of the 4 different symbols may bereceived and symbol-decoded. Thereafter, the LLR for each of the 4symbols may be outputted as the first soft decision value.Alternatively, the LLR for 2 bits may be received and symbol-decoded.Thereafter, the LLR for the 2 bits may be outputted as the first softdecision value.

The symbol interleaver 4020 performs symbol interleaving, as shown inFIG. 19, on the first soft decision value that is outputted from theinner symbol mapper 4019. Then, the symbol interleaver 4020 outputs thesymbol-interleaved first soft decision value to the feedback formatter4021. Herein, the output of the symbol interleaver 4020 also correspondsto a soft decision value. With respect to the changed processing orderof the soft decision values corresponding to the symbols that aregenerated during an intermediate step, wherein the output symbolsoutputted from the block processor 303 of the transmitting system arebeing inputted to the trellis encoding module (e.g., when the symbolspass through the group formatter, the data deinterleaver, the packetformatter, the RS encoder, and the data interleaver), the feedbackformatter 4021 alters (or changes) the order of the output valuesoutputted from the symbol interleaver 4020. Subsequently, the feedbackformatter 4020 outputs values to the trellis decoding unit 4012 in thechanged order.

The soft decision values outputted from the symbol interleaver 4020 arematched with the positions of mobile service data symbols each havingthe size of TBL, which are outputted from the input buffer 4011, so asto be in a one-to-one correspondence. Thereafter, the soft decisionvalues matched with the respective symbol position are inputted to thetrellis decoding unit 4012. At this point, since the main service datasymbols or the RS parity data symbols and known data symbols of the mainservice data do not correspond to the mobile service data symbols, thefeedback formatter 4021 inserts null data in the correspondingpositions, thereby outputting the processed data to the trellis decodingunit 4012. Additionally, each time the symbols having the size of TBLare turbo decoded, no value is fed-back by the symbol interleaver 4020starting from the beginning of the first decoding process. Therefore,the feedback formatter 4021 is controlled by the feedback controller4010, thereby inserting null data into all symbol positions including amobile service data symbol. Then, the processed data are outputted tothe trellis decoding unit 4012.

The output buffer 4022 receives the second soft decision value from thesymbol decoder 4018 based upon the control of the feedback controller4010. Then, the output buffer 4022 temporarily stores the receivedsecond soft decision value. Thereafter, the output buffer 4022 outputsthe second soft decision value to the data deformatter 1006. Forexample, the output buffer 4022 overwrites the second soft decisionvalue of the symbol decoder 4018 until the turbo decoding process isperformed for M number of times. Then, once all M number of turbodecoding processes is performed for a single TBL, the correspondingsecond soft decision value is outputted to the data deformatter 1006.

The feedback controller 4010 controls the number of turbo decoding andturbo decoding repetition processes of the overall block decoder, shownin FIG. 57. More specifically, once the turbo decoding process has beenrepeated for a predetermined number of times, the second soft decisionvalue of the symbol decoder 4018 is outputted to the data deformatter1006 through the output buffer 4022. Thus, the block decoding process ofa turbo block is completed. In the description of the present invention,this process is referred to as a regressive turbo decoding process forsimplicity. At this point, the number of regressive turbo decodingrounds between the trellis decoding unit 4012 and the symbol decoder4018 may be defined while taking into account hardware complexity anderror correction performance. Accordingly, if the number of roundsincreases, the error correction performance may be enhanced. However,this may lead to a disadvantageous of the hardware becoming morecomplicated (or complex).

Meanwhile, the data deinterleaver 1009, the RS decoder 4010, and thedata derandomizer 4011 correspond to blocks required for receiving themain service data. Therefore, the above-mentioned blocks may not benecessary (or required) in the structure of a digital broadcastreceiving system for receiving mobile service data only. The datadeinterleaver 1009 performs an inverse process of the data interleaverincluded in the transmitting system. In other words, the datadeinterleaver 1009 deinterleaves the main service data outputted fromthe block decoder 1005 and outputs the deinterleaved main service datato the RS decoder 4010. The data being inputted to the datadeinterleaver 1009 include main service data, as well as mobile servicedata, known data, RS parity data, and an MPEG header. At this point,among the inputted data, only the main service data and the RS paritydata added to the main service data packet may be outputted to the RSdecoder 4010. Also, all data outputted after the data derandomizer 4011may all be removed with the exception for the main service data. In theembodiment of the present invention, only the main service data and theRS parity data added to the main service data packet are inputted to theRS decoder 4010.

The RS decoder 4010 performs a systematic RS decoding process on thedeinterleaved data and outputs the processed data to the dataderandomizer 4011. The data derandomizer 4011 receives the output of theRS decoder 4010 and generates a pseudo random data byte identical tothat of the randomizer included in the digital broadcast transmittingsystem. Thereafter, the data derandomizer 4011 performs a bitwiseexclusive OR (XOR) operation on the generated pseudo random data byte,thereby inserting the MPEG synchronization bytes to the beginning ofeach packet so as to output the data in 188-byte main service datapacket units.

Meanwhile, the data being outputted from the block decoder 1005 to thedata deformatter 1006 are inputted in the form of a data group. At thispoint, the data deformatter 1006 already knows the structure of the datathat are to be inputted and is, therefore, capable of identifying thesignaling information including system information and the mobileservice data from the data group. Thereafter, the data deformatter 1006outputs the identified signaling information to a block (not shown) forprocessing the signaling information and outputs the identified mobileservice data to the RS frame decoder 1007. More specifically, the RSframe decoder 1007 receives only the RS-encoded and CRC-encoded mobileservice data that are transmitted from the data deformatter 1006.

The RS frame encoder 1007 performs an inverse process of the RS frameencoder included in the transmitting system so as to correct the errorwithin the RS frame. Then, the RS frame decoder 1007 adds the 1-byteMPEG synchronization service data packet, which had been removed duringthe RS frame encoding process, to the error-corrected mobile servicedata packet. Thereafter, the processed data packet is outputted to thederandomizer 1008. The operation of the RS frame decoder 1007 will bedescribed in detail in a later process. The derandomizer 1008 performs aderandomizing process, which corresponds to the inverse process of therandomizer included in the transmitting system, on the received mobileservice data. Thereafter, the derandomized data are outputted, therebyobtaining the mobile service data transmitted from the transmittingsystem. Hereinafter, detailed operations of the RS frame decoder 1007will now be described.

FIG. 58 illustrates a process of grouping a plurality of data groups(e.g., 18 data groups) to create a RS frame and a RS frame reliabilitymap, and also a process of performing data deinterleaving in super frameunits as an inverse process of the transmitting system and identifyingthe deinterleaved RS frame and RS frame reliability map. Morespecifically, the RS frame decoder 907 groups the inputted mobileservice data so as to create a RS frame. The mobile service data havebeen RS-encoded RS frame units by the transmitting system, and theninterleaved in super frame units. At this point, the error correctionencoding process (e.g., the CRC encoding process) may have beenperformed on the mobile service data (as shown in FIG. 5).

If it is assumed that the transmitting system has divided the RS framehaving the size of (N+2)*(187+P) bytes into M number of data groups(wherein, for example, M is equal to 18) and then transmitted thedivided RS frame, the receiving system groups the mobile service data ofeach data group, as shown in FIG. 58( a), so as to create a RS framehaving the size of (N+2)*(187+P) bytes. At this point, if a dummy bytehas been added to at least one of the data groups configuring thecorresponding RS frame and, then, transmitted, the dummy byte isremoved, and a RS frame and a RS frame reliability map are created. Forexample, as shown in FIG. 14, if K number of dummy bytes has been added,the RS frame and RS frame reliability map are created after the K numberof dummy bytes has been removed.

Furthermore, if it is assumed that the RS frame is divided into 18 datagroups, which are then transmitted from a single burst section, thereceiving system also groups mobile service data of 18 data groupswithin the corresponding burst section, thereby creating the RS frame.Herein, when it is assumed that the block decoder 905 outputs a softdecision value for the decoding result, the RS frame decoder may decidethe ‘0’ and ‘1’ of the corresponding bit by using the codes of the softdecision value. 8 bits that are each decided as described above aregrouped to create one data byte. If the above-described process isperformed on all soft decision values of the 18 data groups included ina single burst, the RS frame having the size of (N+2)*(187+P) bytes maybe configured. Additionally, the present invention uses the softdecision value not only to configure the RS frame but also to configurea reliability map. Herein, the reliability map indicates the reliabilityof the corresponding data byte, which is configured by grouping 8 bits,the 8 bits being decided by the codes of the soft decision value.

For example, when the absolute value of the soft decision value exceedsa pre-determined threshold value, the value of the corresponding bit,which is decided by the code of the corresponding soft decision value,is determined to be reliable. Conversely, when the absolute value of thesoft decision value does not exceed the pre-determined threshold value,the value of the corresponding bit is determined to be unreliable.Thereafter, if even a single bit among the 8 bits, which are decided bythe codes of the soft decision value and group to configure one databyte, is determined to be unreliable, the corresponding data byte ismarked on the reliability map as an unreliable data byte.

Herein, determining the reliability of one data byte is only exemplary.More specifically, when a plurality of data bytes (e.g., at least 4 databytes) are determined to be unreliable, the corresponding data bytes mayalso be marked as unreliable data bytes within the reliability map.Conversely, when all of the data bits within the one data byte aredetermined to be reliable (i.e., when the absolute value of the softdecision values of all 8 bits included in the one data byte exceed thepredetermined threshold value), the corresponding data byte is marked tobe a reliable data byte on the reliability map. Similarly, when aplurality of data bytes (e.g., at least 4 data bytes) are determined tobe reliable, the corresponding data bytes may also be marked as reliabledata bytes within the reliability map. The numbers proposed in theabove-described example are merely exemplary and, therefore, do notlimit the scope or spirit of the present invention.

The process of configuring the RS frame and the process of configuringthe reliability map both using the soft decision value may be performedat the same time. Herein, the reliability information within thereliability map is in a one-to-one correspondence with each byte withinthe RS frame. For example, if a RS frame has the size of (N+2)*(187+P)bytes, the reliability map is also configured to have the size of(N+2)*(187+P) bytes. FIG. 58( a′) and FIG. 58( b′) respectivelyillustrate the process steps of configuring the reliability mapaccording to the present invention.

At this point, the RS frame of FIG. 58( b) and the RS frame reliabilitymap of FIG. 58( b′) are interleaved in super frame units (as shown inFIG. 6). Therefore, the RS frame and the RS frame reliability maps aregrouped to create a super frame and a super frame reliability map.Subsequently, as shown in FIG. 58( c) and FIG. 58( c′), a de-permutation(or deinterleaving) process is performed in super frame units on the RSframe and the RS frame reliability maps, as an inverse process of thetransmitting system. Then, when the de-permutation process is performedin super frame units, the processed data are divided into de-permuted(or deinterleaved) RS frames having the size of (N+2)*(187+P) bytes andde-permuted RS frame reliability maps having the size of (N+2)*(187+P)bytes, as shown in FIG. 58( d) and FIG. 58( d′). Subsequently, the RSframe reliability map is used on the divided RS frames so as to performerror correction.

FIG. 59 illustrates example of the error correction processed accordingto embodiments of the present invention. FIG. 59 illustrates an exampleof performing an error correction process when the transmitting systemhas performed both RS encoding and CRC encoding processes on the RSframe (as shown in FIG. 5).

As shown in FIG. 59( a) and FIG. 59( a′), when the RS frame having thesize of (N+2)*(187+P) bytes and the RS frame reliability map having thesize of (N+2)*(187+P) bytes are created, a CRC syndrome checking processis performed on the created RS frame, thereby verifying whether anyerror has occurred in each row. Subsequently, as shown in FIG. 59( b), a2-byte checksum is removed to configure an RS frame having the size ofN*(187+P) bytes. Herein, the presence (or existence) of an error isindicated on an error flag corresponding to each row. Similarly, sincethe portion of the reliability map corresponding to the CRC checksum hashardly any applicability, this portion is removed so that only N*(187+P)number of the reliability information bytes remain, as shown in FIG. 59(b′).

After performing the CRC syndrome checking process, as described above,a RS decoding process is performed in a column direction. Herein, a RSerasure correction process may be performed in accordance with thenumber of CRC error flags. More specifically, as shown in FIG. 59( c),the CRC error flag corresponding to each row within the RS frame isverified. Thereafter, the RS frame decoder 907 determines whether thenumber of rows having a CRC error occurring therein is equal to orsmaller than the maximum number of errors on which the RS erasurecorrection may be performed, when performing the RS decoding process ina column direction. The maximum number of errors corresponds to P numberof parity bytes inserted when performing the RS encoding process. In theembodiment of the present invention, it is assumed that 48 parity byteshave been added to each column (i.e., P=48).

If the number of rows having the CRC errors occurring therein is smallerthan or equal to the maximum number of errors (i.e., 48 errors accordingto this embodiment) that can be corrected by the RS erasure decodingprocess, a (235,187)-RS erasure decoding process is performed in acolumn direction on the RS frame having (187+P) number of N-byte rows(i.e., 235 N-byte rows), as shown in FIG. 59( d). Thereafter, as shownin FIG. 59( e), the 48-byte parity data that have been added at the endof each column are removed. Conversely, however, if the number of rowshaving the CRC errors occurring therein is greater than the maximumnumber of errors (i.e., 48 errors) that can be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process. In addition, the reliability map, which hasbeen created based upon the soft decision value along with the RS frame,may be used to further enhance the error correction ability (orperformance) of the present invention.

More specifically, the RS frame decoder 907 compares the absolute valueof the soft decision value of the block decoder 905 with thepre-determined threshold value, so as to determine the reliability ofthe bit value decided by the code of the corresponding soft decisionvalue. Also, 8 bits, each being determined by the code of the softdecision value, are grouped to form one data byte. Accordingly, thereliability information on this one data byte is indicated on thereliability map. Therefore, as shown in FIG. 59( c), even though aparticular row is determined to have an error occurring therein basedupon a CRC syndrome checking process on the particular row, the presentinvention does not assume that all bytes included in the row have errorsoccurring therein. The present invention refers to the reliabilityinformation of the reliability map and sets only the bytes that havebeen determined to be unreliable as erroneous bytes. In other words,with disregard to whether or not a CRC error exists within thecorresponding row, only the bytes that are determined to be unreliablebased upon the reliability map are set as erasure points.

According to another method, when it is determined that CRC errors areincluded in the corresponding row, based upon the result of the CRCsyndrome checking result, only the bytes that are determined by thereliability map to be unreliable are set as errors. More specifically,only the bytes corresponding to the row that is determined to haveerrors included therein and being determined to be unreliable based uponthe reliability information, are set as the erasure points. Thereafter,if the number of error points for each column is smaller than or equalto the maximum number of errors (i.e., 48 errors) that can be correctedby the RS erasure decoding process, an RS erasure decoding process isperformed on the corresponding column. Conversely, if the number oferror points for each column is greater than the maximum number oferrors (i.e., 98 errors) that can be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column.

More specifically, if the number of rows having CRC errors includedtherein is greater than the maximum number of errors (i.e., 48 errors)that can be corrected by the RS erasure decoding process, either an RSerasure decoding process or a general RS decoding process is performedon a column that is decided based upon the reliability information ofthe reliability map, in accordance with the number of erasure pointswithin the corresponding column. For example, it is assumed that thenumber of rows having CRC errors included therein within the RS frame isgreater than 48. And, it is also assumed that the number of erasurepoints decided based upon the reliability information of the reliabilitymap is indicated as 40 erasure points in the first column and as 50erasure points in the second column. In this case, a (235,187)-RSerasure decoding process is performed on the first column.Alternatively, a (235,187)-RS decoding process is performed on thesecond column. When error correction decoding is performed on all columndirections within the RS frame by using the above-described process, the48-byte parity data which were added at the end of each column areremoved, as shown in FIG. 59( e).

As described above, even though the total number of CRC errorscorresponding to each row within the RS frame is greater than themaximum number of errors that can be corrected by the RS erasuredecoding process, when the number of bytes determined to have a lowreliability level, based upon the reliability information on thereliability map within a particular column, while performing errorcorrection decoding on the particular column. Herein, the differencebetween the general RS decoding process and the RS erasure decodingprocess is the number of errors that can be corrected. Morespecifically, when performing the general RS decoding process, thenumber of errors corresponding to half of the number of parity bytes(i.e., (number of parity bytes)/2) that are inserted during the RSencoding process may be error corrected (e.g., 24 errors may becorrected). Alternatively, when performing the RS erasure decodingprocess, the number of errors corresponding to the number of paritybytes that are inserted during the RS encoding process may be errorcorrected (e.g., 98 errors may be corrected). After performing the errorcorrection decoding process, as described above, a RS frame configuredof 187 N-byte rows (or packet) may be obtained as shown in FIG. 59( e).The RS frame having the size of N*187 bytes is outputted by the order ofN number of 187-byte units. At this point, 1 MPEG synchronization byte,which had been removed by the transmitting system, is added to each187-byte packet, as shown in FIG. 59( f). Therefore, a 188-byte unitmobile service data packet is outputted.

FIG. 60 illustrates an example of a digital broadcast receiving systemaccording to the present invention. The tuner 1002 tunes to a channel toreceive a digital broadcast signal and the demodulator 1002 demodulatesthe received signal. The demodulator further outputs field sync data orknown data including transmission parameters to a transmission parameterdetector 1013. The equalizer 1003 performs channel equalization on thedemodulated signal and outputs the equalized signal to the transmissionparameter detector 1013.

The transmission parameter detector 1013 detects a SCCC mode from thechannel-equalized signal or from the data received from the demodulator1002, and outputs the detected SCCC mode to the block decoder 1005 andthe RS frame decoder 1007, respectively. The block decoder 1005 performsblock decoding on mobile service data included in the channel-equalizedsignal according to the detected SCCC mode. The data deformatter 1006deformats the block-decoded signal and outputs signaling data includedin the block-decoded signal to the transmission parameter detector 1013and further outputs mobile service data included in the block-decodedsignal to the RS frame decoder 1007.

The transmission parameter detector 1013 detects transmission parametersfrom the signals) outputted from the demodulator 1013, the equalizer1003, and/or the data deformatter 1006. For example, the transmissionparameter detector 1013 obtains the location information of the knowndata and detects a SCCC mode and an RS mode from the signal outputtedfrom the demodulator 1013 or the equalizer 1003, and provides thedetected SCCC mode to the block decoder 1005 and the RS frame decoder1007, respectively.

The block decoder 1005 performs error correction decoding on thechannel-equalized signal using the SCCC mode provided from thetransmission parameter detector 1013. The data deformatter 1006deformats the signal outputted from the block decoder 1005 into mobileservice data and signaling data including the transmission parameters,and outputs the mobile service data and the signaling data to the RSframe decoder 1007 and the transmission parameter detector 1013,respectively. The RS frame decoder 1007 performs RS frame decoding onthe mobile service data and outputs the RS-decoded mobile service datato the de-randomizer 1008. The transmission parameter detector 1013performs error correction decoding (e.g., RS decoding) on the signalingdata and obtains transmission parameters other than a SCCC mode. Thetransmission parameters include at least one of a service identifier(ID), an RS mode for regions A and B of a signal frame, an RS mode forregion C of the signal frame, a super frame size (SFS), a permuted frameindex (PFI) indicating the location information of an RS frame in asuper frame, a burst size (BS), a data group index (GI), and a time to anext burst (TNB).

The transmission parameter detector 1013 may output the detected burstinformation including the burst size (BS), the data group index (GI),and the time to a next burst (TNB) to the known sequence detector 1004which provides these information to the burst controller 5000. The burstcontroller 5000 controls power supply to each component of the broadcastreceiving system as shown in FIG. 60 using the burst information.Therefore, the power consumption can be minimized when the broadcastreceiving system is a mobile system.

A burst of data includes a plurality of data groups, and varioustransmission parameters such as an RS mode for regions A and B in a dataframe, an RS mode for region C in the data frame, a super frame size(SFS), a permuted frame index (PFI), and a burst size (BS) for the datagroups may be identical. When a burst of data includes a plurality ofdata groups, there are various ways of detecting and using thetransmission parameters of the data groups. In a first example, thetransmission parameters of all the data groups must be successfullydetected or decoded in order to be used. In a second example, when thetransmission parameters included in a particular data group aresuccessfully detected or decoded, the detected parameters can be usedassuming that the detected parameters of the particular group areidentical to those of the remaining data group(s). Transmissionparameters may include an error due to channel distortion or noise.Therefore, the transmission parameters which are previously detected canbe used if a number of errors included in current transmissionparameters is greater than a predetermined value. Alternatively, newtransmission parameters which are successfully detected can be used ifthe number of errors in the current transmission parameters is greaterthan the predetermined value.

FIG. 61 illustrates a block diagram of the transmission parameterdetector 1013 shown in FIG. 60 in detail. The transmission parameterdetector 1013 includes a mode detector 1011 and a signaling RS decoder1013. The mode detector 1011 detects a SCCC mode from the signaloutputted from the channel equalizer 1003 or from the demodulator 1002and outputs the detected SCCC mode to the block decoder 1005 and the RSframe decoder 1007. The signaling RS decoder 1013 performs RS decodingon the signaling data provided from the data deformatter 1006 (or fromthe block decoder 1005) and obtains transmission parameters. Thetransmission parameters include at least one of a service identifier(ID), an RS mode for regions A and B of a signal frame, an RS mode forregion C of the signal frame, a super frame size (SFS), a permuted frameindex (PFI) indicating the location information of an RS frame in asuper frame, a burst size (BS), a data group index (GI), and a time to anext burst (TNB). The transmission parameters detected by the signalingRS decoder 1013 are applicable to a data group including thetransmission parameters, and the data group index (GI) and the timing toa next burst (TNB) can be renewed or updated for each data group. The RSmode obtained by the signaling RS decoder 1013 is provided to the RSframe decoder which performs error correction decoding on an RS frameincluding the mobile service data using the RS mode.

FIG. 62 illustrates a block diagram of the mode detector 1011 shown inFIG. 61 in detail. The mode detector 1011 includes a pattern correlationunit 1120, a data point controller 1110, and a mode decision unit 1130.The transmission parameter detector 1013 receives known data identifyinga SCCC mode from the demodulator 1002 or the equalizer 1003. The datapoint controller determines the location of the known data and allowsthe pattern correlation unit 1120 to receive data symbols correspondingto a data region including the signaling information. The patterncorrelation unit 1120 calculates correlation values of the data symbols,and the mode decision unit 1130 obtains a SCCC mode from the pattern ofa signal having the maximum correlation value. The detected SCCC mode isprovided to the block decoder 1005 or RS frame decoder.

FIG. 63 illustrates an example of the group burst indicator outputtingthe group valid indicator. Referring to FIG. 63, when a partialcorrelation value of a broadcast signal is checked according to a cycleperiod of a counter, a peak value of the partial correlation valuecorresponding to a data group position (marked as a group) of thebroadcast signal, wherein the data group includes known data, may beindicated. The group burst indicator may output a group valid indicatorcorresponding to the position where the partial correlation valueoccurs.

FIG. 64 illustrates an example of the group burst indicator outputtingthe burst valid indicator. Herein, the group burst indicator may obtainburst information from the signaling information, wherein the burstinformation may include burst cycle information (i.e., one burst cyclecorresponds to 30 fields in the example shown in FIG. 64) and burstlength (i.e., one burst corresponds to 18 fields in the example shown inFIG. 64). In a data group corresponding to a data section includingmobile service data, partial correlation values may periodically occuras shown in the example of FIG. 63.

The burst controller receives the group valid indicator and burst validindicator and may use the received information to control power on/offstates of the receiving system, so as to allow the system to processonly the signal of the mobile service data section including theuser-desired broadcast program. If the broadcast receiving system wishes(or desires) to receive only the mobile service data, the systemconsiders only the mobile service data group included in thecorresponding burst as the valid data. Accordingly, the receiving systemdoes not receive data other than the mobile service data group of thecorresponding burst. When data corresponding to the mobile service datagroup are being processed, even though the corresponding data areincluded in the burst section, the burst controller may use the groupvalid indicator, which is generated while the data that are beingprocessed, so as to turn the power on or off.

FIG. 65 illustrates an example of comparing actual on/off time and theburst section. Referring to FIG. 65, (a) represents a data receivingsection based upon the burst valid indicator and the group validindicator. The broadcast receiving system may turn the power on startingfrom an arbitrary (or random) time prior to a burst starting point or adata group starting point (i.e., set-up time). Alternatively, thebroadcast receiving system may turn the power off starting from anarbitrary (or random) time after a burst ending point or a data groupending point (i.e., hold time). Herein, the set-up time or the hold timemay be adjusted arbitrarily depending upon specific circumstances.

General Digital Broadcast Receiving System

FIG. 66 illustrates a block diagram showing a structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Herein, the demodulating unit of FIG. 36 may be applied inthe digital broadcast receiving system. Referring to FIG. 66, thedigital broadcast receiving system includes a tuner 6001, a demodulatingunit 6002, a demultiplexer 6003, an audio decoder 6004, a video decoder6005, a native TV application manager 6006, a channel manager 6007, achannel map 6008, a first memory 6009, an SI and/or data decoder 6010, asecond memory 6011, a system manager 6012, a data broadcast applicationmanager 6013, a storage controller 6014, a third memory 6015, and a GPSmodule 6020. Herein, the first memory 6009 corresponds to a non-volatilerandom access memory (NVRAM) (or a flash memory). The third memory 6015corresponds to a large-scale storage device, such as a hard disk drive(HDD), a memory chip, and so on.

The tuner 6001 tunes a frequency of a specific channel through any oneof an antenna, cable, and satellite. Then, the tuner 6001 down-convertsthe tuned frequency to an intermediate frequency (IF), which is thenoutputted to the demodulating unit 6002. At this point, the tuner 6001is controlled by the channel manager 6007. Additionally, the result andstrength of the broadcast signal of the tuned channel are also reportedto the channel manager 6007. The data that are being received by thefrequency of the tuned specific channel include main service data,mobile service data, and table data for decoding the main service dataand mobile service data.

According to the embodiment of the present invention, audio data andvideo data for mobile broadcast programs may be applied as the mobileservice data. Such audio data and video data are compressed by varioustypes of encoders so as to be transmitted to a broadcasting station. Inthis case, the video decoder 6004 and the audio decoder 6005 will beprovided in the receiving system so as to correspond to each of theencoders used for the compression process. Thereafter, the decodingprocess will be performed by the video decoder 6004 and the audiodecoder 6005. Then, the processed video and audio data will be providedto the users. Examples of the encoding/decoding scheme for the audiodata may include AC 3, MPEG 2 AUDIO, MPEG 4 AUDIO, AAC, AAC+, HE AAC,AAC SBR, MPEG-Surround, and BSAC. And, examples of the encoding/decodingscheme for the video data may include MPEG 2 VIDEO, MPEG 4 VIDEO, H.264,SVC, and VC-1.

Depending upon the embodiment of the present invention, examples of themobile service data may include data provided for data service, such asJava application data, HTML application data, XML data, and so on. Thedata provided for such data services may correspond either to a Javaclass file for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the mobile service data may correspond to metadata. For example, the meta data be written in XML format so as to betransmitted through a DSM-CC protocol.

The demodulating unit 6002 performs VSB-demodulation and channelequalization on the signal being outputted from the tuner 6001, therebyidentifying the main service data and the mobile service data.Thereafter, the identified main service data and mobile service data areoutputted in TS packet units. An example of the demodulating unit 6002is shown in FIG. 36 to FIG. 65. Therefore, the structure and operationof the demodulator will be described in detail in a later process.However, this is merely exemplary and the scope of the present inventionis not limited to the example set forth herein. In the embodiment givenas an example of the present invention, only the mobile service datapacket outputted from the demodulating unit 6002 is inputted to thedemultiplexer 6003. In this case, the main service data packet isinputted to another demultiplexer (not shown) that processes mainservice data packets. Herein, the storage controller 6014 is alsoconnected to the other demultiplexer in order to store the main servicedata after processing the main service data packets. The demultiplexerof the present invention may also be designed to process both mobileservice data packets and main service data packets in a singledemultiplexer.

The storage controller 6014 is interfaced with the demultiplexer so asto control instant recording, reserved (or pre-programmed) recording,time shift, and so on of the mobile service data and/or main servicedata. For example, when one of instant recording, reserved (orpre-programmed) recording, and time shift is set and programmed in thereceiving system (or receiver) shown in FIG. 66, the correspondingmobile service data and/or main service data that are inputted to thedemultiplexer are stored in the third memory 6015 in accordance with thecontrol of the storage controller 6014. The third memory 6015 may bedescribed as a temporary storage area and/or a permanent storage area.Herein, the temporary storage area is used for the time shiftingfunction, and the permanent storage area is used for a permanent storageof data according to the user's choice (or decision).

When the data stored in the third memory 6015 need to be reproduced (orplayed), the storage controller 6014 reads the corresponding data storedin the third memory 6015 and outputs the read data to the correspondingdemultiplexer (e.g., the mobile service data are outputted to thedemultiplexer 6003 shown in FIG. 66). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 6015 is limited, the compression encoded mobile servicedata and/or main service data that are being inputted are directlystored in the third memory 6015 without any modification for theefficiency of the storage capacity. In this case, depending upon thereproduction (or reading) command, the data read from the third memory6015 pass trough the demultiplexer so as to be inputted to thecorresponding decoder, thereby being restored to the initial state.

The storage controller 6014 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 6015 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 6014compression encodes the inputted data and stored the compression-encodeddata to the third memory 6015. In order to do so, the storage controller6014 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 6014.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 6015, the storage controller6014 scrambles (or encrypts) the input data and stores the scrambled (orencrypted) data in the third memory 6015. Accordingly, the storagecontroller 6014 may include a scramble algorithm (or encryptionalgorithm) for scrambling the data stored in the third memory 6015 and adescramble algorithm (or decryption algorithm) for descrambling (ordecrypting) the data read from the third memory 6015. The scramblingmethod may include using an arbitrary key (e.g., control word) to modifya desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 6003 receives the real-time data outputtedfrom the demodulating unit 6002 or the data read from the third memory6015 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 6003 performs demultiplexing on themobile service data packet. Therefore, in the present invention, thereceiving and processing of the mobile service data will be described indetail. However, depending upon the many embodiments of the presentinvention, not only the mobile service data but also the main servicedata may be processed by the demultiplexer 6003, the audio decoder 6004,the video decoder 6005, the native TV application manager 6006, thechannel manager 6007, the channel map 6008, the first memory 6009, theSI and/or data decoder 6010, the second memory 6011, a system manager6012, the data broadcast application manager 6013, the storagecontroller 6014, the third memory 6015, and the GPS module 6020.Thereafter, the processed data may be used to provide diverse servicesto the users.

The demultiplexer 6003 demultiplexes mobile service data and systeminformation (SI) tables from the mobile service data packet inputted inaccordance with the control of the SI and/or data decoder 6010.Thereafter, the demultiplexed mobile service data and SI tables areoutputted to the SI and/or data decoder 6010 in a section format. Inthis case, it is preferable that data for the data service are used asthe mobile service data that are inputted to the SI and/or data decoder6010. In order to extract the mobile service data from the channelthrough which mobile service data are transmitted and to decode theextracted mobile service data, system information is required. Suchsystem information may also be referred to as service information. Thesystem information may include channel information, event information,etc. In the embodiment of the present invention, the PSI/PSIP tables areapplied as the system information. However, the present invention is notlimited to the example set forth herein. More specifically, regardlessof the name, any protocol transmitting system information in a tableformat may be applied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number.

FIG. 67 illustrates a VCT syntax according to an embodiment of thepresent invention. The VCT syntax of FIG. 67 is configured by includingat least one of a table_id field, a section_syntax_indicator field, aprivate_indicator field, a section_length field, a transport_stream_idfield, a version_number field, a current_next_indicator field, asection_number field, a last_section_number field, a protocol_versionfield, and a num_channels_in_section field.

The VCT syntax further includes a first ‘for’ loop repetition statementthat is repeated as much as the num_channels_in_section field value. Thefirst repetition statement may include at least one of a short_namefield, a major_channel_number field, a minor_channel_number field, amodulation_mode field, a carrier_frequency field, a channel_TSID field,a program_number field, an ETM_location field, an access_controlledfield, a hidden field, a service_type field, a source_id field, adescriptor_length field, and a second ‘for’ loop statement that isrepeated as much as the number of descriptors included in the firstrepetition statement. Herein, the second repetition statement will bereferred to as a first descriptor loop for simplicity. The descriptordescriptors( ) included in the first descriptor loop is separatelyapplied to each virtual channel.

Furthermore, the VCT syntax may further include anadditional_descriptor_length field, and a third ‘for’ loop statementthat is repeated as much as the number of descriptors additionally addedto the VCT. For simplicity of the description of the present invention,the third repetition statement will be referred to as a seconddescriptor loop. The descriptor additional descriptors( ) included inthe second descriptor loop is commonly applied to all virtual channelsdescribed in the VCT.

As described above, referring to FIG. 67, the table_id field indicates aunique identifier (or identification) (ID) that can identify theinformation being transmitted to the table as the VCT. Morespecifically, the table_id field indicates a value informing that thetable corresponding to this section is a VCT. For example, a 0xC8 valuemay be given to the table_id field.

The version_number field indicates the version number of the VCT. Thesection_number field indicates the number of this section. Thelast_section_number field indicates the number of the last section of acomplete VCT. And, the num_channel_in_section field designates thenumber of the overall virtual channel existing within the VCT section.Furthermore, in the first ‘for’ loop repetition statement, theshort_name field indicates the name of a virtual channel. Themajor_channel_number field indicates a ‘major’ channel number associatedwith the virtual channel defined within the first repetition statement,and the minor_channel_number field indicates a ‘minor’ channel number.More specifically, each of the channel numbers should be connected tothe major and minor channel numbers, and the major and minor channelnumbers are used as user reference numbers for the corresponding virtualchannel.

The program_number field is shown for connecting the virtual channelhaving an MPEG-2 program association table (PAT) and program map table(PMT) defined therein, and the program_number field matches the programnumber within the PAT/PMT. Herein, the PAT describes the elements of aprogram corresponding to each program number, and the PAT indicates thePID of a transport packet transmitting the PMT. The PMT describedsubordinate information, and a PID list of the transport packet throughwhich a program identification number and a separate bit sequence, suchas video and/or audio data configuring the program, are beingtransmitted.

FIG. 68 illustrates a service_type field according to an embodiment ofthe present invention. The service_type field indicates the service typeprovided in a corresponding virtual channel. Referring to FIG. 68, it isprovided that the service_type field should only indicate an analogtelevision, a digital television, digital audio data, and digital videodata. Also, according to the embodiment of the present invention, it maybe provided that a mobile broadcast program should be designated to theservice_type field. The service_type field, which is parsed by the SIand/or data decoder 6010 may be provided to a receiving system, as shownin FIG. 66, and used accordingly. According to other embodiments of thepresent invention, the parsed service_type field may also be provided toeach of the audio decoder 6004 and video decoder 6005, so as to be usedin the decoding process.

The source_id field indicates a program source connected to thecorresponding virtual channel. Herein, a source refers to a specificsource, such as an image, a text, video data, or sound. The source_idfield value has a unique value within the transport stream transmittingthe VCT. Meanwhile, a service location descriptor may be included in adescriptor loop (i.e., descriptor{ }) within a next ‘for’ looprepetition statement. The service location descriptor may include astream type, PID, and language code for each elementary stream.

FIG. 69 illustrates a service location descriptor according to anembodiment of the present invention. As shown in FIG. 69, the servicelocation descriptor may include a descriptor_tag field, adescriptor_length field, and a PCR_PID field. Herein, the PCR_PID fieldindicates the PID of a transport stream packet within a programspecified by a program_number field, wherein the transport stream packetincludes a valid PCR field. Meanwhile, the service location descriptorincludes a number_elements field so as to indicate a number of PIDs usedin the corresponding program. The number of repetition of a next ‘for’descriptor loop repetition statement can be decided, depending upon thevalue of the number_elements field. Referring to FIG. 69, the ‘for’ looprepetition statement includes a stream_type field, an elementary_PIDfield, and an ISO_(—)639_language_code field. Herein, the stream_typefield indicates the stream type of the corresponding elementary stream(i.e., video/audio data). The elementary_PID field indicates the PID ofthe corresponding elementary stream. The ISO_(—)639_language_code fieldindicates a language code of the corresponding elementary stream.

FIG. 70 illustrates examples that may be assigned to the stream_typefield according to the present invention. As shown in FIG. 70, ISO/IEC11172 Video, ITU-T Rec. H.262|ISO/IEC 13818-2 Video or ISO/IEC 11172-2constrained parameter video stream, ISO/IEC 11172 Audio, ISO/IEC 13818-3Audio, ITU-T Rec. H.222.0|ISO/IEC 13818-1 private_sections, ITU-T Rec.H.222.0|ISO/IEC 13818-1 PES packets containing private data, ISO/IEC13522 MHEG, ITU-T Rec. H.222.0|ISO/IEC 13818-1 Annex A DSM CC, ITU-TRec. H.222.1, ISO/IEC 13818-6 type A, ISO/IEC 13818-6 type B, ISO/IEC13818-6 type C, ISO/IEC 13818-6 type D, ISO/IEC 13818-1 auxiliary, andso on may be applied as the stream type. Meanwhile, according to theembodiment of the present invention, MPH video stream:Non-hierarchicalmode, MPH audio stream:Non-hierarchical mode, MPH Non-A/Vstream:Non-hierarchical mode, MPH High Priority videostream:Hierarchical mode, MPH High Priority audio stream:Hierarchicalmode, MPH Low Priority video stream:Hierarchical mode, MPH Low priorityaudio stream:Hierarchical mode, and so on may further be applied as thestream type.

As described above, “MPH” corresponds to the initials of “mobile”,“pedestrian”, and “handheld” and represents the opposite concept of afixed-type system. Therefore, the MPH video stream:Non-hierarchicalmode, the MPH audio stream:Non-hierarchical mode, the MPH Non-A/Vstream:Non-hierarchical mode, the MPH High Priority videostream:Hierarchical mode, the MPH High Priority audiostream:Hierarchical mode, the MPH Low Priority video stream:Hierarchicalmode, and the MPH Low priority audio stream:Hierarchical mode correspondto stream types that are applied when mobile broadcast programs arebeing transmitted and received. Also the Hierarchical mode and theNon-hierarchical mode each correspond to values that are used in streamtypes having different priority levels. Herein, the priority level isdetermined based upon a hierarchical structure applied in any one of theencoding or decoding method.

Therefore, when a hierarchical structure-type codec is used, a fieldvalue including the hierarchical mode and the non-hierarchical mode isrespectively designated so as to identify each stream. Such stream typeinformation is parsed by the SI and/or data decoder 6010, so as to beprovided to the video and audio decoders 6004 and 6005. Thereafter, eachof the video and audio decoders 6004 and 6005 uses the parsed streamtype information in order to perform the decoding process. Other streamtypes that may be applied in the present invention may include MPEG 4AUDIO, AC 3, AAC, AAC+, BSAC, HE AAC, AAC SBR, and MPEG-S for the audiodata, and may also include MPEG 2 VIDEO, MPEG 4 VIDEO, H.264, SVC, andVC-1 for the video data.

Furthermore, referring to FIG. 70, in fields using the hierarchical modeand the non-hierarchical mode, such as the MPH video streamNon-hierarchical mode and the MPH audio stream:Non-hierarchical mode,examples of using the MPEG 4 AUDIO, AC 3, AAC, AAC+, BSAC, HE AAC, AACSBR, and MPEG-S for the audio data, and the MPEG 2 VIDEO, MPEG 4 VIDEO,H.264, SVC, and VC-1 for the video data may also be respectively used asreplacements for each of the audio stream and the video stream may beconsidered as other embodiments of the present invention and may,therefore, be included in the scope of the present invention. Meanwhile,the stream_type field may be provided as one of the fields within thePMT. And, in this case, it is apparent that such stream_type fieldincludes the above-described syntax. The STT transmits information onthe current data and timing information. The RRT transmits informationon region and consultation organs for program ratings. The ETT transmitsadditional description of a specific channel and broadcast program. TheEIT transmits information on virtual channel events (e.g., programtitle, program start time, etc.).

FIG. 71 illustrates a bit stream syntax for an event information table(EIT) according to the present invention. In this embodiment, the EITshown in FIG. 71 corresponds to a PSIP table including information on atitle, start time, duration, and so on of an event in a virtual channel.Referring to FIG. 71, the EIT is configured of a plurality of fieldsincluding a table_id field, a section_syntax_indicator field, aprivate_indicator field, a source_ID, a version_numbers_in_sectionfield, a current_next_indicator field, and a num_event field. Morespecifically, the table_id field is an 8-bit field having the value of‘oxCB’, which indicates that the corresponding section is included inthe EIT. The section_syntax_indicator field is a 1-bit field having thevalue of ‘1’. This indicates that the corresponding section passesthrough the section_length field and is in accordance with a genericsection syntax. The private_indicator field corresponds to a 1-bit fieldhaving the value of ‘1’.

Also, the source_ID corresponds to an ID identifying a virtual channelthat carries an event shown in the above-described table. Theversion_numbers_in_section field indicates the version of an elementincluded in the event information table. In the present invention, withrespect to the previous version number, an event change informationincluded in the event information table, wherein the event changeinformation has a new version number is recognized as the latest changein information. The current_next_indicator field indicates whether theevent information included in the corresponding EIT is a currentinformation or a next information. And, finally, the num_event fieldrepresents the number of events included in the channel having a sourceID. More specifically, an event loop shown below is repeated as manytimes as the number of events.

The above-described EIT field is commonly applied to at least one ormore events included in one EIT syntax. A loop statement, which isincluded as “for(j=0;j<num_event_in_section;j++){ }”, describes thecharacteristics of each event. The following fields represent detailedinformation of each individual event. Therefore, the following fieldsare individually applied to each corresponding event described by theEIT syntax. An event_ID included in an event loop is an identifier foridentifying each individual event. The number of the event IDcorresponds to a portion of the identifier for even extended textmessage (i.e., ETM_ID). A start_time field indicates the starting timeof an event. Therefore, the start_time field collects the starting timeinformation of a program provided from an electronic programinformation. A length_in_seconds field indicates the duration of anevent. Therefore, the length_in_seconds field collects the ending timeinformation of a program provided from an electronic programinformation. More specifically, the ending time information is collectedby adding the start_time field value and the length_in_seconds fieldvalue. A title_text( ) field may be used to indicate the tile of abroadcast program.

Meanwhile, the descriptor applied to each event may be included in theEIT. Herein, a descriptors length field indicates the length of adescriptor. Also, a descriptor loop (i.e., descriptor{ }) included in a‘for’ loop repetition statement includes at least one of an AC-3 audiodescriptor, an MPEG 2 audio descriptor, an MPEG 4 audio descriptor, anAAC descriptor, an AAC+ descriptor, an HE AAC descriptor, an AAC SBRdescriptor, an MPEG surround descriptor, a BSAC descriptor, an MPEG 2video descriptor, an MPEG 4 video descriptor, an H.264 descriptor, anSVC descriptor, and a VC-1 descriptor. Herein, each descriptor describesinformation on audio/video codec applied to each event. Such codecinformation may be provided to the audio/video decoder 6004 and 6005 andused in the decoding process.

Finally, the DCCT/DCCSCT transmits information associated with automatic(or direct) channel change. And, the MGT transmits the versions and PIDinformation of the above-mentioned tables included in the PSIP. Each ofthe above-described tables included in the PSI/PSIP is configured of abasic unit referred to as a “section”, and a combination of one or moresections forms a table. For example, the VCT may be divided into 256sections. Herein, one section may include a plurality of virtual channelinformation. However, a single set of virtual channel information is notdivided into two or more sections. At this point, the receiving systemmay parse and decode the data for the data service that are transmittingby using only the tables included in the PSI, or only the tablesincluded in the PSIP, or a combination of tables included in both thePSI and the PSIP. In order to parse and decode the mobile service data,at least one of the PAT and PMT included in the PSI, and the VCTincluded in the PSIP is required. For example, the PAT may include thesystem information for transmitting the mobile service data, and the PIDof the PMT corresponding to the mobile service data (or program number).The PMT may include the PID of the TS packet used for transmitting themobile service data. The VCT may include information on the virtualchannel for transmitting the mobile service data, and the PID of the TSpacket for transmitting the mobile service data.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up. The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective SI tables (i.e., a bouquet associate table(BAT), a running status table (RST), and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRD to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, when the mobile service data correspond toaudio data and video data, it is preferable that the mobile service dataincluded (or loaded) in a payload within a TS packet correspond to PEStype mobile service data. According to another embodiment of the presentinvention, when the mobile service data correspond to the data for thedata service (or data service data), the mobile service data included inthe payload within the TS packet consist of a digital storagemedia-command and control (DSM-CC) section format. However, the TSpacket including the data service data may correspond either to apacketized elementary stream (PES) type or to a section type. Morespecifically, either the PES type data service data configure the TSpacket, or the section type data service data configure the TS packet.The TS packet configured of the section type data will be given as theexample of the present invention. At this point, the data service dataare includes in the digital storage media-command and control (DSM-CC)section. Herein, the DSM-CC section is then configured of a 188-byteunit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge the reception of the databroadcast program including mobile service data. At this point, themobile service data may be transmitted by a data/object carousel method.The data/object carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the SI and/or data decoder6010, the demultiplexer 6003 performs section filtering, therebydiscarding repetitive sections and outputting only the non-repetitivesections to the SI and/or data decoder 6010. The demultiplexer 6003 mayalso output only the sections configuring desired tables (e.g., VCT orEIT) to the SI and/or data decoder 6010 by section filtering. Herein,the VCT or EIT may include a specific descriptor for the mobile servicedata. However, the present invention does not exclude the possibilitiesof the mobile service data being included in other tables, such as thePMT. The section filtering method may include a method of verifying thePID of a table defined by the MGT, such as the VCT, prior to performingthe section filtering process. Alternatively, the section filteringmethod may also include a method of directly performing the sectionfiltering process without verifying the MGT, when the VCT includes afixed PID (i.e., a base PID). At this point, the demultiplexer 6003performs the section filtering process by referring to a table_id field,a version_number field, a section_number field, etc.

As described above, the method of defining the PID of the VCT broadlyincludes two different methods. Herein, the PID of the VCT is a packetidentifier required for identifying the VCT from other tables. The firstmethod consists of setting the PID of the VCT so that it is dependent tothe MGT. In this case, the receiving system cannot directly verify theVCT among the many PSI and/or PSIP tables. Instead, the receiving systemmust check the PID defined in the MGT in order to read the VCT. Herein,the MGT defines the PID, size, version number, and so on, of diversetables. The second method consists of setting the PID of the VCT so thatthe PID is given a base PID value (or a fixed PID value), thereby beingindependent from the MGT. In this case, unlike in the first method, theVCT according to the present invention may be identified without havingto verify every single PID included in the MGT. Evidently, an agreementon the base PID must be previously made between the transmitting systemand the receiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer6003 may output only an application information table (AIT) to the SIand/or data decoder 6010 by section filtering. The AIT includesinformation on an application being operated in the receiver for thedata service. The AIT may also be referred to as an XAIT, and an AMT.Therefore, any table including application information may correspond tothe following description. When the AIT is transmitted, a value of‘0x05’ may be assigned to a stream_type field of the PMT. The AIT mayinclude application information, such as application name, applicationversion, application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_network_id field, the transport_stream_id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 6011 by the SI and/or data decoder 6010.

The SI and/or data decoder 6010 parses the DSM-CC section configuringthe demultiplexed mobile service data. Then, the mobile service datacorresponding to the parsed result are stored as a database in thesecond memory 6011. The SI and/or data decoder 6010 groups a pluralityof sections having the same table identification (table_id) so as toconfigure a table, which is then parsed. Thereafter, the parsed resultis stored as a database in the second memory 6011. At this point, byparsing data and/or sections, the SI and/or data decoder 6010 reads allof the remaining actual section data that are not section-filtered bythe demultiplexer 6003. Then, the SI and/or data decoder 6010 stores theread data to the second memory 6011. The second memory 6011 correspondsto a table and data/object carousel database storing system informationparsed from tables and mobile service data parsed from the DSM-CCsection. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT. When the VCT isparsed, information on the virtual channel to which mobile service dataare transmitted may be obtained.

Also, according to the present invention, the SI and/or data decoder6010 parses the SLD of the VCT, thereby transmitting the stream typeinformation of the corresponding elementary stream to the audio decoder6004 or the video decoder 6005. In this case, the corresponding audiodecoder 6004 or video decoder 6005 uses the transmitted stream typeinformation so as to perform the audio or video decoding process.Furthermore, according to the present invention, the SI and/or datadecoder 6010 parses an AC-3 audio descriptor, an MPEG 2 audiodescriptor, an MPEG 4 audio descriptor, an AAC descriptor, an AAC+descriptor, an HE AAC descriptor, an AAC SBR descriptor, an MPEGsurround descriptor, a BSAC descriptor, an MPEG 2 video descriptor, anMPEG 4 video descriptor, an H.264 descriptor, an SVC descriptor, a VC-1descriptor, and so on, of the EIT, thereby transmitting the audio orvideo codec information of the corresponding event to the audio decoder6004 or video decoder 6005. In this case, the corresponding audiodecoder 6004 or video decoder 6005 uses the transmitted audio or videocodec information in order to perform an audio or video decodingprocess.

The obtained application identification information, service componentidentification information, and service information corresponding to thedata service may either be stored in the second memory 6011 or beoutputted to the data broadcasting application manager 6013. Inaddition, reference may be made to the application identificationinformation, service component identification information, and serviceinformation in order to decode the data service data. Alternatively,such information may also prepare the operation of the applicationprogram for the data service. Furthermore, the SI and/or data decoder6010 controls the demultiplexing of the system information table, whichcorresponds to the information table associated with the channel andevents. Thereafter, an A/V PID list may be transmitted to the channelmanager 6007.

The channel manager 6007 may refer to the channel map 6008 in order totransmit a request for receiving system-related information data to theSI and/or data decoder 6010, thereby receiving the corresponding result.In addition, the channel manager 6007 may also control the channeltuning of the tuner 6001. Furthermore, the channel manager 6007 maydirectly control the demultiplexer 6003, so as to set up the A/V PID,thereby controlling the audio decoder 6004 and the video decoder 6005.

The audio decoder 6004 and the video decoder 6005 may respectivelydecode and output the audio data and video data demultiplexed from themain service data packet. Alternatively, the audio decoder 6004 and thevideo decoder 6005 may respectively decode and output the audio data andvideo data demultiplexed from the mobile service data packet. Meanwhile,when the mobile service data include data service data, and also audiodata and video data, it is apparent that the audio data and video datademultiplexed by the demultiplexer 6003 are respectively decoded by theaudio decoder 6004 and the video decoder 6005. For example, anaudio-coding (AC)-3 decoding algorithm, an MPEG-2 audio decodingalgorithm, an MPEG-4 audio decoding algorithm, an AAC decodingalgorithm, an AAC+ decoding algorithm, an HE AAC decoding algorithm, anAAC SBR decoding algorithm, an MPEG surround decoding algorithm, and aBSAC decoding algorithm may be applied to the audio decoder 6004. Also,an MPEG-2 video decoding algorithm, an MPEG-4 video decoding algorithm,an H.264 decoding algorithm, an SVC decoding algorithm, and a VC-1decoding algorithm may be applied to the video decoder 6005.Accordingly, the decoding process may be performed.

Meanwhile, the native TV application manager 6006 operates a nativeapplication program stored in the first memory 6009, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 6006 displays the user request on a screenthrough a graphic user interface (GUI), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 6006 and the databroadcasting application manager 6013. Furthermore, the native TVapplication manager 6006 controls the channel manager 6007, therebycontrolling channel-associated operations, such as the management of thechannel map 6008, and controlling the SI and/or data decoder 6010. Thenative TV application manager 6006 also controls the GUI of the overallreceiving system, thereby storing the user request and status of thereceiving system in the first memory 6009 and restoring the storedinformation.

The channel manager 6007 controls the tuner 6001 and the SI and/or datadecoder 6010, so as to managing the channel map 6008 so that it canrespond to the channel request made by the user. More specifically,channel manager 6007 sends a request to the SI and/or data decoder 6010so that the tables associated with the channels that are to be tuned areparsed. The results of the parsed tables are reported to the channelmanager 6007 by the SI and/or data decoder 6010. Thereafter, based onthe parsed results, the channel manager 6007 updates the channel map6008 and sets up a PID in the demultiplexer 6003 for demultiplexing thetables associated with the data service data from the mobile servicedata.

The system manager 6012 controls the booting of the receiving system byturning the power on or off. Then, the system manager 6012 stores ROMimages (including downloaded software images) in the first memory 6009.More specifically, the first memory 6009 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 6011 so as to provide the user with the dataservice. If the data service data are stored in the second memory 6011,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 6009 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stored managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied, the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory6009 upon the shipping of the receiving system, or be stored in thefirst memory 6009 after being downloaded. The application program forthe data service (i.e., the data service providing application program)stored in the first memory 6009 may also be deleted, updated, andcorrected. Furthermore, the data service providing application programmay be downloaded and executed along with the data service data eachtime the data service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 6013 operates thecorresponding application program stored in the first memory 6009 so asto process the requested data, thereby providing the user with therequested data service. And, in order to provide such data service, thedata broadcasting application manager 6013 supports the graphic userinterface (GUI). Herein, the data service may be provided in the form oftext (or short message service (SMS)), voice message, still image, andmoving image. The data broadcasting application manager 6013 may beprovided with a platform for executing the application program stored inthe first memory 6009. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 6013 executing the data serviceproviding application program stored in the first memory 6009, so as toprocess the data service data stored in the second memory 6011, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiver that is not equipped with an electronic mapand/or a GPS system in the form of at least one of a text (or shortmessage service (SMS)), a voice message, a graphic message, a stillimage, and a moving image. In this case, when a GPS module 6020 ismounted on the receiving system, as shown in FIG. 66, the GPS module6020 receives satellite signals transmitted from a plurality of lowearth orbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager6013.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 6011, the first memory 6009, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 6013, the dataservice data stored in the second memory 6011 are read and inputted tothe data broadcasting application manager 6013. The data broadcastingapplication manager 6013 translates (or deciphers) the data service dataread from the second memory 6011, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal. In other words, the data broadcasting application manager 6013uses the current position information and the graphic information, sothat the current position information can be processed and provided tothe user in a graphic format.

FIG. 72 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 72, the digitalbroadcast receiving system includes a tuner 7001, a demodulating unit7002, a demultiplexer 7003, a first descrambler 7004, an audio decoder7005, a video decoder 7006, a second descrambler 7007, an authenticationunit 7008, a native TV application manager 7009, a channel manager 7010,a channel map 7011, a first memory 7012, a data decoder 7013, a secondmemory 7014, a system manager 7015, a data broadcasting applicationmanager 7016, a storage controller 7017, a third memory 7018, atelecommunication module 7019, and a GPS module 7020. Herein, the thirdmemory 7018 is a mass storage device, such as a hard disk drive (HDD) ora memory chip. Also, during the description of the digital broadcast (ortelevision or DTV) receiving system shown in FIG. 72, the componentsthat are identical to those of the digital broadcast receiving system ofFIG. 66 will be omitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descramble the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an authentication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 7004 and 7007, and the authentication means will bereferred to as an authentication unit 7008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.72 illustrates an example of the descramblers 7004 and 7007 and theauthentication unit 7008 being provided inside the receiving system,each of the descramblers 7004 and 7007 and the authentication unit 7008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 7008, the scrambled broadcastingcontents are descrambled by the descramblers 7004 and 7007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 7008 and thedescramblers 7004 and 7007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 7001 and the demodulating unit 7002. Then, the system manager7015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 7002 may be included as ademodulating means according to embodiment of the present invention asdescribed in FIG. 36 to FIG. 65. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 7015 decides that the received broadcasting contentshave been scrambled, then the system manager 7015 controls the system tooperate the authentication unit 7008. As described above, theauthentication unit 7008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 7008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 7008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advance, with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 7008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 7008 determines that the two types ofinformation conform to one another, then the authentication unit 7008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or antherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem-specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 7008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 7008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 7008 determines that the information conform to eachother, then the authentication unit 7008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 7008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the above-mentioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 7015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 7015 transmits thepayment information to the remote transmitting system through thetelecommunication module 7019.

The authentication unit 7008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 7008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 7008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 7008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 7004 and 7007. Herein,the first and second descramblers 7004 and 7007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 7004 and 7007, so as to perform the descrambling process.More specifically, the first and second descramblers 7004 and 7007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 7004 and 7007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 7004 and 7007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 7004 and 7007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 7015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 7012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 7008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 7008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 7015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 7012 upon the shipping of the presentinvention, or be downloaded to the first memory 7012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 7016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 7003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 7004 and 7007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 7004 and7007. Each of the descramblers 7004 and 7007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 7004 and 7007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 7018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced). Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 7017, the storage controller 7017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 7018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associated with theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 7019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 7019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information). Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 7019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module7019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1x EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile internet,WiBro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 7019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 7003 receives either the real-time data outputted from thedemodulating unit 7002 or the data read from the third memory 7018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 7003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 7004 receives the demultiplexed signals from thedemultiplexer 7003 and then descrambles the received signals. At thispoint, the first descrambler 7004 may receive the authentication resultreceived from the authentication unit 7008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 7005 and the video decoder 7006 receive the signalsdescrambled by the first descrambler 7004, which are then decoded andoutputted. Alternatively, if the first descrambler 7004 did not performthe descrambling process, then the audio decoder 7005 and the videodecoder 7006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 7007 and processed accordingly.

As described above, the digital broadcasting system and data processingmethod according to the present invention have the following advantages.More specifically, the digital broadcasting system and data processingmethod according to the present invention is robust against (orresistant to) any error that may occur when transmitting mobile servicedata through a channel. And, the present invention is also highlycompatible to the conventional system. Moreover, the present inventionmay also receive the mobile service data without any error even inchannels having severe ghost effect and noise.

By inserting known data in specific positions (or places) within a dataregion, the present invention may enhance the receiving performance ofthe receiving system in an environment undergoing frequent channelchanges. Additionally, when multiplexing the mobile service data withthe main service data, by multiplexing the data in a bus structure, thepower consumption level of the receiving system may be reduced.Moreover, by using known data information in order to perform channelequalization, the receiving system may perform channel equalization withmore stability.

Furthermore, by performing at least one of an error correction encodingprocess, an error detection encoding process, and a row permutationprocess in super frame units on the mobile service data and transmittingthe processed data, the present invention may provide robustness to themobile service data, thereby enabling the data to effectively respond tothe frequent change in channels. Finally, the present invention is evenmore effective when applied to mobile and portable receivers, which arealso liable to a frequent change in channel and which require protection(or resistance) against intense noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of processing broadcast data in abroadcast transmitter, the method comprising: randomizing broadcastservice data; first encoding the randomized broadcast service data toadd parity data; second encoding the first-encoded broadcast servicedata at a code rate of D/E, wherein D<E; first interleaving thesecond-encoded broadcast service data; encoding signaling data forsignaling the broadcast service data; modulating the first-interleavedbroadcast service data and the encoded signaling data; and transmittingthe modulated data, wherein the signaling data include information forindicating the code rate.
 2. The method of claim 1, further comprising:second interleaving the first-interleaved broadcast service data.
 3. Themethod of claim 1, further comprising: randomizing the signaling data.4. The method of claim 1, wherein the broadcast service data aretransmitted through one or more delivery units included in a frame. 5.The method of claim 4, wherein the code rate is independently applied toeach of the one or more delivery units.
 6. The method of claim 4,wherein the signaling data further include a number of delivery unitscontained in the frame.
 7. A broadcast transmitter for processingbroadcast data, the broadcast transmitter comprising: a randomizerconfigured to randomize broadcast service data; a first encoderconfigured to first encode the randomized broadcast service data to addparity data; a second encoder configured to second encode thefirst-encoded broadcast service data at a code rate of D/E, wherein D<E;a first interleaver configured to first interleave the second-encodedbroadcast service data; an encoder configured to encode signaling datafor signaling the broadcast service data; a modulator configured tomodulate the first-interleaved broadcast service data and the encodedsignaling data; and a transmitting unit configured to transmit themodulated data, wherein the signaling data include information forindicating the code rate.
 8. The broadcast transmitter of claim 7,further comprising: a second interleaver configured to second interleavethe first-interleaved broadcast service data.
 9. The broadcasttransmitter of claim 7, wherein the randomizer is further configured torandomize the signaling data.
 10. The broadcast transmitter of claim 7,wherein the broadcast service data are transmitted through one or moredelivery units included in a frame.
 11. The broadcast transmitter ofclaim 10, wherein the code rate is independently applied to each of theone or more delivery units.
 12. The broadcast transmitter of claim 10,wherein the signaling data further include a number of delivery unitscontained in the frame.